JPH0347644B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] More specifically, the present invention relates to a method for producing a propylene-α-olefin block copolymer. Polymerization of other α-olefins or polymerization of propylene and other The present invention relates to a method for producing an α-olefin block copolymer with high reactor volumetric efficiency by copolymerizing α-olefin with α-olefin.

[Conventional technology]

Regarding the polymerization of α-olefins such as ethylene and propylene, the performance of polymerization catalysts has improved significantly in recent years, and the yield of polymer per catalyst component has dramatically increased. was sufficiently small, making it possible to omit the catalyst removal step.

On the other hand, the polymerization methods for these α-olefins include slurry polymerization in an inert hydrocarbon solvent, bulk polymerization in a liquefied monomer such as liquefied propylene, and gas phase polymerization in a gas phase. Although it is legal, in recent years it has become popular because gas phase polymerization does not use a solvent, so there is no need for solvent recovery or purification steps, and it is easy to recover monomers and dry the polymer product. It has started to attract attention.

In the field of propylene and other α-olefin block copolymers, propylene polymer is produced in the first stage, and in the second stage, other α-olefins are polymerized in the gas phase, or propylene and other α-olefins are copolymerized in the gas phase. A block copolymerization method is known.

The gas-phase block copolymerization method has economical reasons as mentioned above, as well as product diversification, compared to methods in which the subsequent polymerization is carried out in an inert hydrocarbon solvent or in liquid propylene. There are also some advantages.

However, in gas phase polymerization, the reaction rate is slow because the monomer concentration is relatively low, and catalysts with good particle properties are required to form a good fluidized bed. It has been pointed out that a catalyst with excellent properties is essential, and that various difficulties are involved, such as problems with equipment for good flow and mixing, heat removal problems, and adhesion problems. In particular, adhesion inside the reactor not only becomes a major hindrance to long-term stable operation, but also causes a decline in quality.

[Problem that the invention seeks to solve]

The present inventors mainly focused on propylene in the latter stage.
Regarding the phenomena of adhesion and deterioration of powder properties within the α-olefin gas phase copolymerization reactor, we have conducted intensive studies on the causes and countermeasures. As a result, in the gas phase polymerization reactor and its gas circulation system, low molecular weight polymers of ethylene and propylene are likely to be produced due to the action of the organoaluminum component used as a cocatalyst, and in some cases, oily substances may be formed. It has been found that these low molecular weight polymers are the cause of adhesion and agglomeration inside the reactor, deterioration of powder properties, etc.

[Means for solving problems]

Therefore, the present inventors investigated various methods for suppressing the production of these low molecular weight polymers, and found that
By supplying a specific compound into the gas-phase polymerization reaction system in the latter stage, it suppresses the production of low molecular weight polymers without affecting the polymerization reaction at all, and reduces the deterioration of powder properties, adhesion inside the reactor, and clumping. The inventors have discovered that this can be prevented, and have arrived at the present invention.

The gist of the present invention is to polymerize propylene or propylene and a small amount of other α-olefin in the presence of a catalyst to obtain a propylene polymer, and then to polymerize propylene and another α-olefin or other α-olefin in the gas phase. This method of producing an alpha-olefin block copolymer is characterized in that a phosphite is supplied to the subsequent gas phase polymerization system.

The present invention will be sequentially explained below.

In the present invention, the polymerization catalyst used includes a titanium-containing solid catalyst component and an organoaluminum compound, but is not particularly limited, and any known catalyst can be used.

As the titanium-containing solid catalyst component, a known carrier-supported catalyst component containing a solid magnesium compound, a titanium compound component, and a halogen component can also be used, but a catalyst component containing titanium trichloride as the main component is preferable. As the material containing titanium trichloride as a main component, conventionally known titanium trichloride can be used. For example, titanium trichloride that has been activated by ball milling; titanium trichloride that has been extracted with a solvent; β-type titanium trichloride that has been treated with a complexing agent such as an ether, and then treated with titanium tetrachloride. Al
Titanium trichloride with an atomic ratio of 0.15 or less to Ti: In the presence of ethers, titanium tetrachloride is treated with an organoaluminum compound to form a liquid,
One example is titanium trichloride, which is further heated to form a solid with an Al content of 0.15 or less in terms of atomic ratio to Ti.

Among these titanium trichlorides, particularly preferred are those having an aluminum content of 0.15 or less, preferably 0.1 or less, more preferably 0.02 or less in terms of the atomic ratio of aluminum to titanium, and containing a complexing agent. The content of the complexing agent is 0.001 or more, preferably 0.01 or more in molar ratio of the complexing agent to titanium trichloride in the solid titanium trichloride-based catalyst complex. Specifically, titanium trichloride, the atomic ratio of aluminum to titanium in titanium trichloride is 0.15.
The following formula AlR ¹ pX ₃ -p (wherein R ¹ is a carbon number of 1 to 20
hydrocarbon group, X is a halogen atom, p is 0≦p≦
2) containing a complexing agent in a molar ratio of 0.001 or more to aluminum halide and titanium trichloride, such as those with the formula TiCl ₃ .
(AlR ¹ pX ₃ −p) _a・(C) _r t (In the formula, R ¹ is a carbon number of 1 to
20 hydrocarbon groups, X is a halogen atom, p is a number of 0≦p≦2, C is a complexing agent, a is a number of 0.15 or less, and t is a number of 0.001 or more. Of course, in addition to the TiCl ₃ component, the AlR ¹ pX-p component, and the complexing agent C component, a small amount of iodine, and some or all of the chlorine in titanium trichloride are iodine. Alternatively, it may be substituted with bromine, or may contain an inorganic solid for a carrier such as MgCl ₂ or MgO, or an olefin polymer powder such as polyethylene or polypropylene. Examples of the complexing agent C include ethers, thioethers, ketones, carboxylic acid esters, amines, carboxylic acid amides, and polysiloxanes, among which ethers and thioethers are particularly preferred. As an ether or thioether,
General formula R″-O-R or R″-S-R″ (in the formula, R″,
R represents a hydrocarbon group having 15 or less carbon atoms. ). Examples of AlR ¹ pX ₃ -p include AlCl ₃ and AlR ¹ Cl ₂ .

Furthermore, it is particularly preferable that the solid titanium trichloride-based catalyst complex has a halo of maximum intensity at a position corresponding to the strongest peak position of α-type titanium trichloride in its X-ray diffraction pattern (near 2 = 329°). . Furthermore, when producing a solid titanium trichloride catalyst complex, 150
Those that have not been subjected to thermal history at temperatures exceeding 0.degree. C. are preferred. Furthermore, the cumulative pore volume between 20 Å and 500 Å pore radius measured by mercury porosimeter method is 0.02
cm ³ /g or more, especially 0.03 cm ³ /g to ^{0.15 cm 3} /g, which is characterized by a pore volume with an extremely fine pore diameter, in that there is no need to remove amorphous polymers. Particularly preferred.

However, such a solid titanium trichloride-based catalyst complex can be prepared from a liquid containing titanium trichloride liquefied in the presence of (a) ether or thioether at 150°C;
Precipitate at the following temperature.

(b) Solid titanium trichloride obtained by reducing titanium tetrachloride with an organic aluminum compound or metal aluminum is treated with a complexing agent and a halogen compound.

It can be easily manufactured by methods such as.
Methods (a) and (b) above have already been proposed in Japanese Patent Publication No. 55-8451.
No. 55-8452, No. 53-24194, No. 55-8003,
No. 54-41040, No. 54-28316, JP-A-53-
No. 12796, No. 52-91794, No. 55-116626, No. 53
-3356, 52-40348, 58-36928, 59
-12905, 59-13630, etc. Furthermore, in addition to methods (a) and (b),
As described in No. 27871, to solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound, an ether compound of 0.5 to 5 in molar ratio to the titanium trichloride is added, and 50 ~120
Those prepared by heating to 0.degree. C. and then separating the solids may also be used.

The organoaluminum compound used as a cocatalyst for the titanium-containing solid catalyst component has the general formula AlR ² X ₃ -m (wherein R ² is a hydrocarbon group having 1 to 20 carbon atoms; m is 3≧m＞1.5
). If the titanium-containing solid catalyst component is a carrier-supported catalyst component containing a solid magnesium compound, AlR ₃ ² or
Preference is given to using a mixture of AlR ₃ ² and AlR ₂ ² X. On the other hand, when the titanium-containing solid catalyst component is mainly composed of titanium trichloride, AlR ₂ ² is used, but diethylaluminum chloride, di-normal propyl aluminum chloride, dihexyl aluminum chloride, and sinormal octylaluminum chloride are generally used. It is preferable to do so.

The titanium trichloride and organoaluminum compounds shown above are generally organoaluminum compounds/
The molar ratio of titanium trichloride is 1 to 30, preferably 2 to 15
used within the range.

In the present invention, the above catalyst may be used as it is, but it is preferable to pre-polymerize a small amount of olefin onto the catalyst made of titanium trichloride and an organoaluminum compound as a pretreatment.

The above method involves adding titanium trichloride and an organoaluminum compound to an inert solvent such as hexane, heptane, etc., and adding propylene, ethylene,
It is sufficient to supply an olefin such as butene-1 or a mixture thereof for polymerization. This pretreatment is generally referred to as prepolymerization, and known polymerization conditions can be used as they are. Polymerization temperature is 30-70°C. The higher the polymerization rate per unit weight of titanium trichloride, the better; however, from an equipment or economic point of view, it is 0.1 to 100 g-polymer/g-
It is generally in the range of TiCl ₃ .

Furthermore, a molecular weight regulator such as hydrogen may be added during prepolymerization.

Furthermore, it is preferable that the prepolymerization is carried out uniformly in a batch manner. This prepolymerization is effective in improving polymer properties such as bulk density.

An additive for improving stereoregularity may be used as a third component in the catalyst made of titanium trichloride and an organoaluminum compound described above. For this purpose, various electron-donating compounds and hydrocarbon compounds containing N atoms, O atoms, P atoms, Si atoms, etc. are used. Such electron-donating compounds include compounds containing one or more electron-donating atoms or groups, such as ethers, polyethers, alkylene oxides, furans, amines, trialkylphosphines, triarylphosphines, and pyridines. , quinolines, phosphoric acid esters, phosphorous acid esters, phosphoric acid amides, phosphine oxides, trialkyl phosphites, triarylphosphites, ketones, carboxylic acid esters, carboxylic acid amides, and the like. Among these, the preferred one is
Carboxylic acid esters such as ethyl benzoate, methyl benzoate, phenyl acetate, and methyl methacrylate; glycine esters such as dimethylglycine ethyl ester and dimethylglycine phenyl ester; triaryls such as triphenyl phosphite and trinonyl phenyl phosphite; Examples include phosphite.

Furthermore, aromatic hydrocarbons such as benzene, toluene, and xylene may also be used as the third component.
The amount of the third component added is generally in a molar ratio of 0.0001 to 5, preferably 0.001 to 1, relative to titanium trichloride.

The polymerization method in the main polymerization of propylene carried out in the first stage can be carried out by known slurry polymerization, slurry polymerization in a liquefied monomer, gas phase polymerization, or the like.
These polymerization methods may be either batchwise or continuous, and the reaction conditions are 1 to 100 atm, preferably 5 to 40
The reaction is carried out under atmospheric pressure at a temperature of 50 to 90°C, preferably 60 to 80°C. In slurry polymerization, inert hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, etc. used in ordinary olefin polymerization are used as the polymerization medium. Preferably normal hexane, normal heptane, cyclohexane,
Benzene and toluene are preferably used. Moreover, propylene itself can also be used as a medium.

As a method for controlling the molecular weight of the produced polymer, a known molecular weight controlling agent such as hydrogen or diethylzinc may be appropriately added to the polymerization reaction.

Although propylene alone may be polymerized in the first stage of the present invention, propylene and a small amount of other α-olefin may be used in combination. Other α-olefins include α-olefins such as ethylene, butene-1,4-methylpentene-1, etc.
-Olefins, etc., and the amount thereof is small enough that the product does not lose its properties as a propylene polymer, for example, 10% by weight or less based on propylene.

The propylene polymer obtained by the first-stage polymerization is transferred to the second-stage gas phase polymerization vessel without deactivating the catalyst contained therein, with or without removing a portion of the reaction medium. That is, when the polymer is obtained by a solvent polymerization method, inert hydrocarbons and unreacted monomers are removed using a centrifuge, a liquid cyclone, or the like. Furthermore, when liquid propylene itself is used as the medium, it can be sent directly to a gas phase polymerization vessel in addition to similar known solid-liquid separation means.

The most important technical feature of the present invention is that by newly adding phosphite to the gas phase polymerization system in the latter stage, it is possible to generate low molecular weight polymers of α-olefin monomers such as ethylene and propylene. suppress,
As a result, adhesion within the reactor, agglomeration phenomenon, and deterioration of powder properties can be prevented, and a good fluidized bed can be formed and stable operation can be achieved.

Phosphite esters used in the present invention include phosphite aliphatic esters such as trimethyl phosphite, triethyl phosphite, and tripropyl phosphite, and phosphorous alicyclic esters such as tricyclohexyl phosphite. Examples include esters and aromatic esters of phosphorous acid such as triphenyl phosphite.

Further, although these phosphite esters are different from the electron-donating compound used in the propylene polymerization in the previous step, they may be the same. That is, if it has excellent polymerization properties (polymerization activity, stereoregularity, etc.) in the propylene polymerization system in the first stage, it is added to the first stage as a third component, and it is also added to the gas phase polymerization system in the second stage. be able to.

The phosphite can be added directly to the gas phase reactor or diluted in an inert hydrocarbon solvent or liquid propylene, or added to the α-olefin or propylene and other α-olefins. It can also be supplied directly in a mixed gas, or after being dissolved or diluted in an inert hydrocarbon solvent, liquid propylene, etc.

The amount of phosphite used varies depending on the amount of organoaluminum compound present in the gas-phase polymerization system, but usually, it is relative to the amount of organoaluminum compound supplied in the first stage, or when organoaluminum is added to the gas-phase polymerization system in the second stage. When adding a compound (for example, Japanese Patent Publication No. 55-7464, Japanese Patent Publication No. 53-30686, Japanese Patent Publication No. 56-30686)
No. 151713) has a molar ratio of phosphite/organoaluminium of 0.0001 to 0.0001 relative to the total amount of both.
1, preferably 0.001 to 0.5. If the amount added is too large, the polymerization activity of gas phase polymerization will decrease,
Undesirable. On the other hand, if the amount is too small, the effect of suppressing the formation of low molecular weight polymers will not be sufficiently exhibited.

In addition, a method of newly adding an inert hydrocarbon to the gas phase polymerization system in the latter stage (for example, JP-A-57-31905)
Also, the method of the present invention can be used in combination with a method of adding a silicone compound (for example, Japanese Patent Application No. 1734560/1982) and is effective.

In the present invention, α is polymerized or copolymerized in a gas phase.
- As the olefin, used is an α-olefin having 2 to 8 carbon atoms, preferably ethylene or an ethylene-propylene mixture.

The conditions for gas phase polymerization are usually 30 to 100℃ and 1 to 50℃.
Kg/cm ² , and the polymerization ratio of the α-olefin block copolymerization portion in the subsequent stage to the total polymer is 3.
Polymerization or copolymerization is carried out to 50% by weight, preferably 10 to 30% by weight. When using a more preferred embodiment of ethylene-propylene mixed gas,
The composition of the gas is 10 to 90 mol% propylene based on the sum of ethylene and propylene, preferably 20 to 90 mol%.
It is 80 mol%.

The production method of the present invention basically consists of a first stage of polymerizing propylene or propylene and a small amount of other α-olefin to obtain a propylene polymer, and a first stage of polymerizing propylene with a small amount of other α-olefin.
- a subsequent stage for gas phase polymerization of olefins or propylene and other α-olefins; but,
In the present invention, the subsequent gas phase polymerization of α-olefin can be carried out in multiple stages, and the polymerization temperature, hydrogen temperature, monomer composition, and reaction amount ratio can also be changed in each reactor.

In the present invention, the equipment used for the subsequent gas phase polymerization is not limited, and known equipment such as a fluidized bed, a stirred tank, a fluidized bed with a stirring device, a moving bed, etc. is preferably used, and the polymerization is carried out continuously or batchwise.

After the completion of gas phase polymerization, the polymer extracted continuously or batchwise is subjected to inactivation treatment or deashing treatment with alkylene oxide, alcohol, water, etc., and removal of amorphous polymer with a solvent, etc., as necessary. It's okay to get old.

The feature of the method of the present invention is that the addition of phosphite to the gas phase polymerization system in the latter stage suppresses the formation of low molecular weight polymers of α-olefin, which cause adhesion and sticking, and provides good powder properties. What you get,
Adhesion to the vessel wall and clumping phenomena are eliminated, a good fluidity state is achieved, long-term stable operation is possible in terms of process and quality, and there is little effect on polymerization behavior such as the activity of gas phase polymerization. The goal is not to affect

〔Example〕

The present invention will be described below with reference to Examples, but the present invention is not limited thereto unless it exceeds the gist thereof.

In the following Examples and Comparative Examples, bulk density, n-
The hexane extraction residue was measured by the following method.

(1) Bulk density: JIS K-6721 (2) Residue from n-hexane extraction Remaining amount (% by weight) after extraction with boiling n-hexane for 3 hours using an improved Soxhlet extractor.

Example 1 (A) Preparation of solid titanium trichloride 5.15% of purified toluene was placed in a 10 volume autoclave that was sufficiently purged with nitrogen at room temperature.
While stirring, 651 g (5 moles) of n-butyl ether,
949 g (5 moles) of titanium tetrachloride and 286 g (2.4 moles) of diethylaluminum chloride were added;
A brown homogeneous solution was obtained.

The temperature was then raised to 40°C, and after 30 minutes, precipitation of purple fine particles was observed, but the temperature was maintained at 40°C for 2 hours.

Then 315g of titanium tetrachloride was added and heated to 98°C.
The temperature rose to . After being kept at 98°C for about 1 hour, the granular purple solid was separated and washed with n-hexane to give about 1 hour.
800 g of solid titanium trichloride was obtained.

(B) Production of titanium trichloride containing propylene polymer (pretreatment) Purified n-hexane 5 was placed in 10 autoclaves that were sufficiently purged with nitrogen, and 195 g of diethylaluminium chloride and the solid titanium trichloride obtained in (A) above were added. After charging 250g of TiCl ₃ , keep the temperature at 40℃ and add propylene gas with stirring.
Contact treatment was carried out by blowing 250 g into the gas phase for about 60 minutes.

Next, the solid component was allowed to settle and the supernatant liquid was removed by decantation, and washed several times with n-hexane to obtain a propylene polymer-containing solid titanium trichloride.

(C) Production of propylene-ethylene block copolymer Two reactors with agitators with capacities of 1,000 and 400 are connected in series, and in addition, one stirred fluidized tank type gas phase polymerization tank with a capacity of 1,500 is connected in series. They were connected in series, and in the first and second reactors homopolymerization of propylene was carried out in liquefied propylene, and in the third reactor, copolymerization of propylene and ethylene was carried out by gas phase polymerization.

The first reaction tank contained liquefied propylene, 4.0 g/hr of the catalyst component obtained in (B) above, 10 g/hr of co-catalyst diethyl aluminum chloride, 0.52 g/hr of methyl methacrylate, and hydrogen as a molecular weight regulator.
0.15Kg/hr was continuously supplied. The polymerization temperature was 70°C in the first tank and 67°C in the second tank, and the slurry was continuously extracted from the first tank and supplied to the second tank. The average residence time is the total of the 1st tank and 2nd tank.
It took 4.0 hours.

The polymer slurry from the second tank is continuously transferred to the third tank.
Gas phase polymerization was carried out while maintaining the temperature at 60° C. and the pressure at 15 kg. ethylene in gas phase,
The composition of propylene was adjusted to propylene/(ethylene+propylene)=65 mol% _H2 /(ethylene+propylene)=15 mol%. Additionally, triphenyl phosphite was supplied to the circulating gas of this gas phase polymerization system at a rate of 1.6 g/hr.

The average residence time in this gas phase reactor is 2.5 hours, and the polymer powder continuously extracted from the third tank is separated from unreacted gas and then treated with propylene oxide vapor to produce 45 kg of powdered polymer. /
Obtained at a rate of hr.

This operation was continued for 30 days, and stable operation of the entire system was achieved. After the reactor was opened, no deposits or lumps were observed inside the reactor, and no oily residue was observed in the comparative example. No formation of any substance was observed.

The average weight ratio of homopolymerization and copolymerization of the polymer obtained during this period was 85/15. The bulk density of the powder was 0.46 g/cc, and the amount remaining after extraction with n-hexane was 97.2%.

Comparative Example 1 Continuous operation for 14 days was carried out in the same manner as in Example 1 except that triphenyl phosphite was not supplied to the gas phase polymerization system.

During this period, the formation of oily substances was observed at the bottom of the gas phase reactor distribution plate, and the pressure loss of the distribution plate tended to increase over time. The bulk density of the obtained polymer powder was also low, 0.38 to 0.40 g/cc, and the residual amount after extraction with n-hexane was 92.6%.

Further, after the operation was completed, the reactor was opened, and sticky substances and fine particles were found to be attached to the upper part of the reactor freeboard section, and formation of lumps was observed around the shaft of the stirring blade and around the stay section. Furthermore, deposits were also formed on the dispersion plate.

〔Effect of the invention〕

According to the present invention, the production of low molecular weight polymers is suppressed without reducing polymerization activity, and adhesion to the inner wall of the reactor and clumping phenomena are eliminated to achieve a good fluidity state, which improves quality from a process perspective. It also enables long-term stable operation.

Claims (1)

[Claims] 1. Propylene is polymerized in the presence of a catalyst, and then α other than propylene is polymerized without deactivating the catalyst.
- An α-olefin block copolymer characterized in that a phosphite ester is supplied to the subsequent gas phase polymerization system in a method of polymerizing or copolymerizing olefin or propylene and other α-olefins in a gas phase. manufacturing method. 2. The method according to claim 1, wherein the polymerization catalyst comprises titanium trichloride and dialkyl aluminum chloride. 3. A patent claim characterized in that the polymerization catalyst has an aluminum content in an atomic ratio of aluminum to titanium of 0.15 or less and is composed of a solid titanium trichloride catalyst complex containing a complexing agent and an organoaluminum compound. The method described in Scope 1. 4 The polymerization catalyst is a solid titanium trichloride-based catalyst complex, and the pore radius measured by the mercury porosimeter method is 20
The method for producing a block copolymer according to claim 1, which uses a block copolymer having a cumulative pore volume of 0.02 cm ³ /g or more between Å and 500 Å. 5 The polymerization catalyst is a solid titanium trichloride catalyst complex,
Claim 1, which is precipitated at a temperature of 150°C or less from a liquid containing titanium trichloride liquefied in the presence of an ether or thioether.
The method for producing the block copolymer described in Section 1. 6 The polymerization catalyst is a solid titanium trichloride-based catalyst complex, which is obtained by treating solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound or metal aluminum, and treating it with a complexing agent and a halogen compound. A method for producing a block copolymer according to claim 1.