JPH0788403B2 - Method for producing polyolefin - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a process for producing polyolefins using a novel catalyst system, substantially while forming polymer particles. More specifically, it relates to a method for stably producing a polyolefin while substantially forming polymer particles using a carrier-supported catalyst produced by the novel method.

BACKGROUND ART It is already known that an olefin polymer (including a copolymer) can be obtained at low pressure using a homogeneous catalyst obtained from a transition metal complex and an organoaluminum compound, and studies on the reaction mechanism of a Ziegler catalyst are known. It is often used for etc.

However, since its polymerization activity is extremely low, it is rarely used for industrial production of polyolefins. However, it has recently been known and noted that a very high polymerization activity can be obtained by using a soluble catalyst composed of bis (cyclopentadiene) zirconium dichloride and methylalumoxane (JP-A-58-19309). I'm flying

This catalyst system is very sensitive to hydrogen, in addition to having very high polymerizability per transition metal compound, and is suitable for producing low molecular weight polyethylene (so-called wax). It has properties such as the ability to obtain a random copolymer with and has a very high practical value. However, this catalyst system is so-called "slurry polymerization" or "slurry polymerization" in which polymerization is performed substantially while forming polymer particles. When used for "gas phase polymerization", stable operation is difficult due to various problems such as formation of coarse polymer, decrease in bulk density of polymer, adhesion of polymer to reactor wall and decrease in heat transfer coefficient. .

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is to improve the above-mentioned drawbacks and, when used for slurry polymerization or gas phase polymerization of olefin, is highly active and does not cause adhesion of polymer, etc., and stably produces polyolefin. To provide a catalyst system capable of

Means for Solving Problems As a result of earnest study to achieve the above object (A) General formula (cyclopentadienyl) ₂ MR _m X _2-m ( _m =
0 to 2, M = Ti or Zr, R is an alkyl group having 1 to 6 carbon atoms, X is a halogen atom), and (B) a reaction product of a trialkylaluminum and water ( C) An activator compound as a co-catalyst is added to a polymerization reactor when a polyolefin is produced substantially in the presence of a solid catalyst component obtained by supporting it on an inorganic oxide carrier while forming polymer particles. By not supplying
The inventors have found that the above objects can be achieved and have reached the present invention.

According to the method of the present invention in which both the specific transition metal compound and the activator compound are supported on the porous carrier and supplied to the reactor,
It was unexpected that the polymer adhesion in the slurry polymerization or the gas phase polymerization could be prevented and the stable operation could be realized. Further, in the polymerization using a Ziegler catalyst, it is well known to supply an activator compound (mainly an organoaluminum compound) to a polymerization reactor. It is a preferred embodiment to feed the drug compound to the reactor. Therefore, it is quite unexpected and surprising from the prior art that the effect of the present invention is exhibited by the method of not supplying the activator compound to the reactor as in the present invention.

The transition metal compound used in the present invention is represented by the general formula (cyclopentadienyl) ₂ MR ′ _m X _2-m . M is a transition metal such as titanium or zirconium, R '
Is an alkyl group having 1 to 6 carbon atoms, X is a halogen atom, and m is a number of 0 to 2. Representative examples of the suitable ones are biscyclopentadienyl zirconium dichloride and biscyclopentadienyl titanium dichloride. In the present invention, a reaction product of trialkylaluminum and water is used as one of the catalyst components. Specific examples of trialkylaluminum include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisobutylaluminum or , And mixtures thereof. Particularly favorable results are achieved when using trimethylaluminum. The reaction of trialkylaluminum with water is a condensation reaction, and the product obtained varies depending on the molar ratio of the reaction components and the reaction conditions. (In the formula, R ² is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 or more.) A condensate or a mixture thereof. The above reaction can be easily carried out by gradually adding a predetermined amount of water to a trialkylaluminum dissolved in an inert hydrocarbon solvent such as toluene, and slightly heating it as necessary. It is also possible to use water of crystallization such as hydrate zinc sulfate heptahydrate.

The amount of water used is usually 0.1 to 1.5 mol ratio, preferably 0.5 to 1.2 mol ratio, based on trialkylaluminum. When this reaction is removed, the catalytic activity drops sharply. The inorganic oxide carrier used for this is an oxide of a metal of Group IIa, Group IIIa, Group IXa and Group IXb of the Periodic Table, and specific examples thereof include silica, alumina, silica-alumina and Agnesia. , Titania, etc. The properties of these oxides differ depending on the type and production method, but the carrier preferably used in the present invention has a surface area of 10 m ²
/ g or more, the average pore diameter is 50 Å or more, and the particle diameter is 100 μm or less. Further, in order to use these carriers for the purpose of the present invention, it is preferable that the amount of adsorbed water and hydroxyl groups on the surface is as small as possible, and for that purpose, it is necessary to perform a baking treatment at a high temperature. The firing temperature is preferably 500 to 800 ° C, 500
Below ℃, the surface hydroxyl groups cannot be reduced enough,
Also, it is not preferable because sintering occurs at 800 ° C. or higher and pores are destroyed. Particularly preferred results in the present invention are 50
It can be obtained when silica or alumina calcined at 0 to 800 ° C. is used.

In carrying the transition metal compound (A) and the reaction product of trialkylaluminum and water (B) on the inorganic oxide carrier, both of these components may be carried at the same time. You may carry one component.
Further, the loading ratio of both components is 30 mol of the reaction product of trialkylaluminum and water to 1 mol of the transition metal compound.
It is preferable to use more than the molar amount (Al / M ≧ 30), and if it is more than this, sufficient activity cannot be obtained.

The method of supporting both components on the inorganic oxide carrier can be carried out by impregnation by dissolving both components (or one component) in an inert solvent and then mixing the carrier with this solution. The supporting temperature is generally 100 ° C or lower, preferably 0 to 40 ° C. The solid catalyst component thus obtained is washed several times with an inert solvent and then used as a slurry as it is or after being dried and then powdered. Polymerization according to the present invention, which is substantially performed while forming polymer particles, is so-called slurry polymerization or gas phase polymerization. The solvent used in the case of slurry polymerization is, for example, an inert hydrocarbon such as butane, isobutane, pentane, hexane, cyclohexane or toluene, alone or in a mixture. Alternatively, the α-olefin can be used as it is as a solvent. The polymerization temperature is generally -10 ° C.
To 150 ° C, and practically 0 ° C to 100 ° C. The gas phase polymerization is carried out in a gas phase state substantially free of a solvent, and a known reactor such as a fluidized bed stirring tank can be used.
The polymerization temperature is usually 0 to 150 ° C., preferably 20 to 100
℃.

In Ziegler-catalyzed polymerization, it is common to supply both a transition metal compound and a liquid activator compound to a polymerization reactor to carry out the polymerization, but in the present invention, it is supported on an inorganic oxide carrier. Other than the reaction product of trialkylaluminum and water, no additional activator compound is supplied to the polymerization reactor. The activator compound is a known activator for so-called Ziegler polymerization, such as an organoaluminum compound, an organomagnesium compound, and an organozinc compound.

The polyolefin in the present invention includes polyethylene, copolymers of ethylene and other α-olefins, and homopolymers of α-olefins, but the effect of the present invention is to obtain polyethylene and ethylene and other α-olefins. It is particularly exerted when producing the copolymer of. Typical examples of α-olefins used include propylene, butene-1,
Hexene-1,4-methylpentene-1 can be mentioned.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

In the examples and comparative examples, the melt flow index (hereinafter referred to as “MFI”) was measured according to JIS K-6758 at a temperature of 230 ° C. and a load of 2.16 Kg. The content CE was measured by infrared absorption spectroscopy. The melting point was measured using a DSC II type scanning differential thermal analyzer manufactured by Perkin Elmer.

Example 1 Reaction of trialkylaluminum compound with water 60 ml of toluene and 60 mmol of trimethylaluminum were added to a nitrogen-substituted 300 ml three-necked flask at -30 ° C.
30 mmol of water are added dropwise. After addition, gradually increase the temperature,
Stirring was continued at 40 ° C. for 10 hours to complete the reaction, and a reaction product was obtained.

Production of Solid Catalyst Component In a 300 ml three-necked flask purged with nitrogen, 50 ml of a toluene solution of biscyclopentadienylzirconium dichloride (0.02 mol /) and 50 mmol of a reaction product of trimethylaluminum and water were added. To this, 5 g of SiO ₂ (Fuji Davison # 952) that had been calcined at 800 ° C. was added, and after stirring for 5 hours, the solid catalyst component was obtained by washing with toluene several times. Zr9m in 1g of solid catalyst component
g, Al140mg was included.

Polymerization of ethylene 3 Isobutane 2 in a stainless steel autoclave
Then, 2 g of the above solid catalyst component was added, and the internal temperature was raised to 70 ° C. Then, hydrogen was added at a gauge pressure of 3 kg / cm ² , and ethylene was further injected to carry out polymerization for 1 hour while maintaining the ethylene partial pressure at 10 kg / cm ² . Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 175 g of a white powdery polymer was obtained. No polymer adhesion was found in the autoclave.

When the molecular weight of this polymer was measured by GPC, w = 6
It was 000.

Example 2 Copolymerization of ethylene and propylene 2 g of the solid catalyst component obtained in Example 1 was placed in a nitrogen-substituted stainless steel autoclave No. 3 and 700 g of propylene was added, and the internal temperature was raised to 30 ° C. Then, ethylene was injected under pressure to continue the polymerization for 1 hour while supplying ethylene so that the ethylene concentration was kept at 10 mol% (based on propylene). Then, the supply of ethylene was stopped and the content gas was released to the outside of the system to terminate the polymerization. As a result, 18
2 g of granular polymer was obtained. Further, there was no adhesion of the polymer inside the autoclave. The obtained polymer is
It was a random copolymer having MFI = 1.3, CE = 68%, and melting point = 45 ° C.

Example 3 Reaction of trialkylaluminum with water 100 mmol of copper sulfate pentahydrate was placed in a nitrogen-substituted 300 ml three-necked flask and suspended in 100 ml of toluene. Then, 300 mmol of trimethylaluminum is added at 30 ° C., and the reaction is continued at that temperature for 48 hours. Then, the reaction product was separated by a glass filter to obtain a solution of the reaction product. When toluene was removed by distillation, 8.2 g of white crystals were obtained.

Production of Solid Catalyst Component A solid catalyst component was obtained in the same manner as in Example 1 except that the reaction product of trimethylaluminum and water obtained by the above method was used. Zr9.2m per 1g of solid catalyst component
It contained g Al 155 mg.

Polymerization of ethylene Polymerization of ethylene was carried out in the same manner as in Example 1 except that 1 g of the solid catalyst component obtained above was used. As a result, the autoclave has no polymer adhesion,
283 g of a white powdery polymer was obtained. W = 560 by GPC
It was 0.

Example 4 A solid catalyst component was obtained in the same manner as in Example 3 except that biscyclopentadienyl titanium dichloride was used instead of biscyclopentadienyl zirconium dichloride. Ti 4.8 mg and Al 180 mg were contained per 1 g of this solid catalyst component.

Copolymerization of ethylene and propylene A copolymer of ethylene and propylene was carried out in the same manner as in Example 2 except that 2 g of the solid catalyst component obtained above was used. As a result, 126 g of a white granular polymer was obtained without any polymer adhesion to the autoclave. The obtained polymer was a random copolymer having MFI = 0.8, CE = 70% and melting point = 50 ° C.

Example 5 Copolymerization of ethylene and butene-1 1 g of the solid catalyst component obtained in Example 3 and isobutane 2 were placed in a nitrogen-substituted 3 stainless steel autoclave, and the internal temperature was raised to 70 ° C. Then, butene-1 90
Then, ethylene was injected under pressure until the partial pressure reached 5 kg / cm ² . Polymerization was carried out for 1 hour while feeding ethylene so as to maintain the pressure. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, no polymer was attached to the autoclave, and 195 g of a white powdery polymer was obtained. The MFI of this polymer is 1.5,
The density was 0.921 g / cc.

Example 6 A solid catalyst component was obtained in exactly the same manner as in Example 3 except that biscyclopentadienylzirconium dichloride was used in place of biscyclopentadienylzirconium dichloride in Example 3. Zr 12.3 mg and Al 172 mg were contained per 1 g of this solid catalyst component.

Copolymerization of Ethylene and Propylene Copolymerization of ethylene and propylene was performed in exactly the same manner as in Example 2 except that 2 g of the solid catalyst component obtained above was used. As a result, no polymer was attached to the autoclave, and 223 g of a white granular polymer was obtained. This polymer was a random copolymer having MFI = 0.5, CE = 66% and melting point = 47 ° C.

Example 7 Polymerization of Ethylene 300 g of a high-density polyethylene powder was charged into a stainless steel autoclave having an internal volume of 3 and replaced with nitrogen, and the mixture was heated at 90 ° C. for 1 hour.
It was dried under reduced pressure for an hour. Then, the pressure was returned to normal pressure under nitrogen, and the temperature in the system was raised to 70 ° C.

1 g of the solid catalyst component obtained in Example 1 was added thereto, and then ethylene was injected under pressure until the partial pressure reached 10 kg / cm ² .
While feeding ethylene to maintain its pressure, 1
Polymerization was carried out for a time.

Then, the content gas was released to the outside of the system to terminate the polymerization.

As a result, no polymer was attached to the autoclave, and 95 g of a white powdery polymer (amount obtained by subtracting 300 g of high-density polyethylene powder) was obtained.

Comparative Example 1 Polymerization of ethylene In Example 1, instead of the solid catalyst component, 0.2 mmol of biscyclopentadienyldiuconium dichloride,
And the reaction product of trimethylaluminum and water 10 mmol
Polymerization of ethylene was performed in the same manner as in Example 1 except that was used. As a result, most of the produced polymer was firmly attached to the inner wall of the autoclave and the stirrer, and the heat transfer coefficient was remarkably lowered, so that temperature control became difficult and stable operation could not be performed.

Comparative Example 2 Copolymerization of ethylene and propylene In Example 2, except that 2 mmol of the reaction product of trimethylaluminum and water obtained in Example 1 was added to the autoclave as an additional activator compound. The copolymerization of ethylene and propylene was carried out in the same manner as in. As a result, 178 g of a powdery polymer was obtained, but the polymer was firmly attached to the inner wall of the autoclave and the stirrer. The deposit was dissolved and removed with xylene, reprecipitated in methanol, dried and weighed to find 23 g.

Comparative Example 3 Copolymerization of Nitylene and Propylene Copolymerization of ethylene and propylene was carried out in the same manner as in Comparative Example 2 except that triethylaluminum was used instead of the reaction product of trimethylaluminum and water. I did. As a result, 65 g of a powdery polymer was obtained, but adhesion of the polymer was found on the inner wall of the autoclave and the stirrer. The collected deposit was 17 g.

Three-necked flask 300ml produced nitrogen substitution Comparative Example 4 the solid catalyst component, biscyclopentadienyl zirconium dichloride toluene solution (0.02 mol /) 50 ml was added, followed by Si O ₂ (Fuji Dejison Co. was calcined at 800 ° C. , # 952) 5g was added. After continuing stirring for 5 hours, by washing with toluene several times,
A solid catalyst product was obtained. Zr 13 mg was contained in 1 g of the solid catalyst component.

Copolymerization of ethylene and propylene To a nitrogen-substituted 3 stainless steel autoclave, 2 g of the above solid catalyst component and 10 mmol of the reaction product of trimethylaluminum and water obtained in Example 3 were added, and then 700 g of propylene was added, Raise the internal temperature to 30 ° C. Then, ethylene was injected under pressure, and the polymerization was continued for 1 hour while supplying ethylene so that the ethylene concentration was maintained at 10 mol% (based on propylene). Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 54 g of a granular polymer was obtained, but the polymer was firmly attached to the inner wall of the autoclave and the stirrer. The amount of deposits collected was 15 g.

[Brief description of drawings]

FIG. 1 is a flow chart for clarifying the polymerization process of the present invention.

Claims (1)

[Claims] 1. (A) General formula (cyclopentadienyl) ₂ M
R _m X _2-m (M = Ti or Zr, R is an alkyl group having 1 to 6 carbon atoms, X is a halogen atom, m = 0 to 2) and (B) trialkyl A polyolefin is produced substantially in the presence of a solid catalyst component obtained by supporting a reaction product of aluminum and water on (C) an inorganic oxide carrier, and substantially forming polymer particles. Method for producing polyolefin