JPS62232404A - Polymerization of ethylene of alpha-olefin - Google Patents

Abstract

PURPOSE:To obtain a polymer of high quality, by deactivating the remaining catalyst when switching a catalyst system in polymerizing ethylene or an alpha- olefin by alternately using specified two catalyst systems of different properties in the same plant. CONSTITUTION:Two catalyst systems, i.e., a nonsupported catalyst system (A) based on titanium trichloride (-containing composition) and an organoaluminum compound and a supported catalyst system (B) based on an organoaluminum compound and a supported catalyst formed by allowing a magnesium compound to support a transition metal component are prepared. Ethylene or an alpha-olefin is (co)polymerized by alternately using the catalyst systems A and B in the same plant. When switching from catalyst A to catalyst B or from catalyst B to catalyst A in the above polymerization, the polymerization process and its main upstream lines are treated with a catalyst deactivator (e.g., ethanol or diethylene glycol monopropyl ether) to deactivate the remaining catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the (co)polymerization of ethylene or α-olefins, and more specifically, the present invention relates to the (co)polymerization of ethylene or α-olefins, and more specifically, the copolymerization of ethylene or α-olefins.
The present invention relates to a method for (co)polymerizing ethylene or alpha-olefins using two or more catalyst systems.

Catalytic systems using titanium trichloride and organoaluminum compounds have traditionally been used for the (co)polymerization of ethylene or α-olefins, but recently a catalyst system consisting of a solid component in which a transition metal compound is supported on a magnesium compound and an organoaluminum compound has been used. Highly active supported catalysts have been put into practical use.

From a polymerization perspective, it is preferable to use a highly active supported catalyst, but the properties of the resulting polymer are slightly different.
There is also a need to produce polymers polymerized with traditionally used titanium trichloride type catalysts.

There is no problem if polymerization with different catalyst systems is produced in two plants, but in order to operate the production equipment efficiently, it is necessary to produce it in one plant, but when two catalysts with different properties are mixed, the properties may change. Different polymers are produced, which is undesirable.

The two catalyst systems mentioned above have different molecular weights of the polymers produced, but when the hydrogen concentration used as a molecular weight regulator is the same, the titanium trichloride catalyst produces a high molecular weight polymer, while the supported catalyst system produces a low molecular weight polymer, preventing catalyst contamination. Polymers with different molecular weights are mixed into the material, which deteriorates the quality of the polymer. In particular, when changing from a titanium trichloride catalyst system to a supported type catalyst system, it is necessary to polymerize at a low hydrogen concentration, so even if a very small amount of titanium trichloride is mixed in, an ultra-high molecular weight polymer will be produced, so it was necessary to use a film. This is a big problem because Fin Shuai occurs in some cases.

In order to prevent catalyst contamination during the continuous polymerization process, we investigated a method of cleaning the catalyst supply tank, catalyst storage tank, etc. with an inert solvent before the polymerization process, but it was found that the removal of catalyst attached to valves and other small parts was incomplete. Therefore, even after repeating the cleaning operation, the Fin Shuai did not disappear.

As a result of studies conducted by the present inventors to avoid the above problems, (A) (a) titanium trichloride or titanium trichloride composition (b) non-supported catalyst system containing an organoaluminum compound as a main component (B) ( a) Supported catalyst in which a transition metal component is supported on a magnesium compound (b) Supported catalyst system in which the main component is an organoaluminum compound (A) to (B) or (B) to (^) The present inventors have found that the present invention can be solved by treating the main part before the polymerization process with a catalyst-based deactivator (^) and/or (B) when making the change.

The titanium trichloride or titanium trichloride composition used in the method of the present invention may be a known titanium trichloride used in polyolefin polymerization, such as one obtained by reducing titanium tetrachloride with hydrogen, metallic aluminum, an organoaluminum compound, etc. titanium trichloride or titanium trichloride composition further pulverized or pulverized with addition of an electron donor, etc.;
Alternatively, examples include titanium trichloride or titanium trichloride compositions produced by treating these with an electron donor and, if necessary, an electron acceptor such as titanium tetrachloride.

As the organoaluminum compound used in the method of the present invention, known organoaluminum compounds which are used as catalyst components of polyolefins in combination with transition metal compounds are used, such as trimethylaluminum, triethylaluminum, tri-propylaluminum, tri-iso -phthyl aluminum, tri-n-octyl aluminum, diethylaluminium monochloride, di-n-propyl monochloride, di-1so-
Butyl monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminium monobromide, diethylaluminium monofluoride, diethylaluminium monoiodide,
Examples include isoprenylaluminum and triphenylaluminum.

As the carrier catalyst in which the transition metal component (a) component of the carrier type catalyst system (B) is supported on a magnesium compound, a known carrier catalyst is used, and as an example of a typical production method, magnesium chloride is mixed with titanium trichloride, titanium trichloride, A method in which magnesium chloride is co-pulverized with titanium tetrachloride, etc., a method in which magnesium chloride is treated with a known electron donor such as ethyl benzoate or isobutyl phthalate, and then further treated with titanium tetrachloride, and a method in which magnesium chloride is dissolved in alcohol, etc. Examples include a method of subsequently treating with titanium tetrachloride, and a method of treating magnesium alkoxide or a magnesium salt of a fatty acid with titanium tetrachloride.

As for the organoaluminum compound used as the component (b) of the catalyst system (B), the above-mentioned organoaluminum compounds are used.

In addition, various known additives, particularly electron-donating compounds such as O, N, P, S, and Si, may be added to the catalyst systems (A) and (B) for the purpose of improving the crystallinity of the produced polymer. It can also be polymerized. Typical examples of additives include ethyl benzoate, methyl P-)ruylate, methyl P-anisate, and phenyltrimethoxysilane.

The deactivating agent used in the method of the present invention is not particularly limited, and any known deactivating agent can be used as long as it is a catalyst decomposing agent for a so-called Ziegler-Natsuta catalyst or a deactivating agent that substantially eliminates the activity of the catalyst. Particularly preferably, a known deactivating agent can be used. Component (a) of catalyst systems (A) and (B) is solubilized in an inert solvent, and the deactivator is soluble in the inert solvent.

However, the above-mentioned preferred conditions are not essential, since it is sufficient that the catalyst does not enter the polymerization system and show activity as a polymerization catalyst.

Typical examples of the deactivating agent used in the present invention include alcohols, organic acids, metal alcoholates, organic acid metal salts, complexing agents, ketones, acid anhydrides, alkylene oxides, amines, etc. Examples include methanol, ethanol, 2-ethylhexanol, diethylene glycol, diethylene glycol monopropyl ether, and propylene oxide.

There are various polymerization processes for polyolefins, but in the present invention, even if the components (a) in the catalyst system (A) or (B) entering the polymerization system are unmixed or mixed, the activity of either one is substantially reduced. It is necessary to eliminate it, and it is necessary to treat the main part with a deactivator before the polymerization process.

Examples of common polymerization processes include (A) or (B) directly from the reservoir of (a) catalyst component, or diluted with an inert solvent, or mixed with (b) component, and optionally in small amounts. Since the catalyst is pretreated with a monomer and then supplied to the polymerization vessel, it is necessary to treat the main portion where the catalyst is mixed with the deactivator of the present invention.

In the treatment with a deactivating agent carried out in the method of the present invention, the deactivating agent may be added to the place where the catalyst mixing occurs as described above, but generally it is first washed with an inert solvent to reduce the amount of residual catalyst before switching. It is preferable to do so.

However, even with careful cleaning, catalyst contamination cannot be avoided, so simple cleaning is preferable. A quenching agent is then added in the presence or absence of an inert solvent. The amount of the deactivator used varies depending on its type and processing conditions, but is at least 0.1 mol, preferably at least 1 mol, based on the remaining catalyst components.

Next, preferably, heating is performed to bring the remaining catalyst into contact with the deactivator. Heating is often effective in dissolving the remaining catalyst.

Subsequently, the quencher (or containing an inert solvent) is discharged, and if necessary, it is washed with an inert solvent (if necessary, an organoaluminum compound is added during washing to make the quencher harmless). The catalyst to be switched next can be charged.

Through the above treatment, a catalyst system that provides a polymer of good quality can be prepared. During the treatment with a deactivating agent in the method of the present invention, the polymerization step is performed by deactivating the catalyst with the deactivating agent and then replacing it with a solvent or monomer to reduce the amount of the deactivating agent and switching the catalyst. It is preferable to prepare for polymerization.

The method of the present invention can be used for ethylene, α
- In the polymerization and copolymerization of olefins, all known polymerization methods such as solution method, suspension method, bulk polymerization, and gas phase polymerization can be applied.

Example 1 In this example, catalyst systems (A) and (B) shown below were used.

(A) (a) AA type buried titanium Aluminum chloride and modified titanium trichloride crushed with addition of diphenyl ether and washed with heptane (b) Diethylaluminium monochloride (B) (
a) A carrier catalyst obtained by heating a composition consisting of magnesium chloride and isobutyl phthalate together with titanium tetrachloride and washing with heptane. (b) Triethyl 7-fluminium. Furthermore, (C) phenyltrimethoxysilane was used as a stereoregularity improver.

Connect two 200 β tanks equipped with a stirrer and baffles, use (I) as the catalyst storage tank, and add 50g/g of the catalyst (a) component.
A catalyst line was created in which the catalyst was stored at a concentration of 5 g/l and then supplied to the polymerization system by charging II) into a catalyst supply tank from (I) through a catalyst meter and diluting it to a concentration of 5 g/l. It is assembled.

For (1), (^) Hebutane slurry of modified titanium trichloride as component (a) was used, and for (II), diethylaluminum monochloride was used as (A) (a) and (b) components in AI/Ti moles. The catalyst was charged at a ratio of 3 to continue supplying the catalyst to the polymerization system. Catalyst level in (■) and (II) tanks is 20%
When the amount reached, the supply of the catalyst system was stopped and a catalyst switching operation was performed.

That is, 300 g of zero-order diethylene glycol isopropyl ether, which was washed by adding heptane 1601 to tanks (1) and (II), stirring, and discharging the catalyst slurry;
Add heptane 2001 and heat at 70°C for 1 hour. After draining the contents of (n), move (1) from (■) to (II) to clean the line to (II). After the liquid was drained, the contents were discharged.

Subsequently, the same operation was repeated twice using only heptane.

(B) in tanks (1) and (II) prepared as above.
(a) The catalyst components were charged.

(B) (a) Sampling the catalyst component from tank (II) and using triethylaluminum and phenyltrimethoxysilane as the catalyst component, hydrogen in the gas phase was heated to 2 Volχ at 70°C.
Polymerization was carried out in heptane to obtain a polymer with [η) (tetralin at 135° C.) of 1.63 and II 97.3%.

A stabilizer was added to the obtained polymer and a film was produced by using a 201III extruder at a temperature of 230°C, and a good film with few fish eyes was obtained.

Example 2 In the method of Example 1, 300 g of 2-ethylhexanol was used instead of diethylene glycol isopropyl ether.
Exactly the same experiment was repeated except that .

In this case as well, a good film with less line shear f was obtained.

Comparative Example 1 In the method of Example 1, the addition of diethylene glycol isopropyl ether was omitted and cleaning with only heptane was performed.
Repeated 0 times, tanks (I) and (It) as in Example 1.
The catalyst component (B) (a) was sampled from the tank (1I) and polymerized in the same manner as in Example 1 to make a film. A film with a large number of eyes and commercial value could not be obtained.

Claims (1)

[Claims] In the process of polymerizing or copolymerizing ethylene or α-olefin, (A) (a) titanium trichloride or a titanium trichloride composition (
b) Non-supported catalyst containing an organoaluminum compound as the main component (B) (a) Supported catalyst system in which a transition metal component is supported on a magnesium compound (b) Supported catalyst system containing an organoaluminum compound as the main component (B) When changing the catalyst system from A) to (B) or from (B) to (A), it is recommended to treat the main part before the polymerization process with a deactivator for the catalyst system (A) and/or (B). A method for polymerizing or copolymerizing ethylene or α-olefin.