JPS61207405A - Polymerization of ethylene - Google Patents

Abstract

PURPOSE:To produce polyethylene of a high MW, by polymerizing ethylene or copolymerizing ethylene with an alpha-olefin at a high temperature and a high pressure by using a specified catalyst component. CONSTITUTION:Ethylene is polymerized or copolymerized with an alpha-olefin at a temperature >=125 deg.C and a pressure >=200kg/cm<2> in the presence of a solid catalyst component (A) containing titanium, magnesium or chlorine, an organoaluminum compound (B) and a heterocyclic compound (C) having a basic skeleton of the formula (wherein R<2> is a hydrocarbon group, R<3>, R<4>, R<5> and R<6> are each H or a hydrocarbon group, at least either of R<3> and R<4> and at least either of R<5> and R<6> are each a hydrocarbon group, R<3> and R<4> or R<5> and R<6> may be combined together to form a ring and X is N or O).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the
This invention relates to a method for polymerizing ethylene to produce high molecular weight polyethylene under pressure greater than atmospheric pressure. More specifically, the present invention relates to a process for polymerizing ethylene under high pressure and high temperature using a Ziegler catalyst having key features in the catalyst used.

In recent years, as seen in British Patent No. 221142, a method has been developed in which ethylene is polymerized at high temperature and high pressure using a high-pressure polyethylene polymerization apparatus and incorporating a Ziegler type aS. is proposed.

This method uses linear low density polyethylene (LLDPI)
It is advantageous for industrial production. In other words, existing high-pressure polyethylene production equipment can be used as is, and no new equipment investment is required.

Furthermore, since ethylene polymerization is an exothermic reaction, heat removal is a major problem in the process, but this method allows the temperature difference between the internal temperature and the cooling medium to be increased when polymerization is carried out at high temperatures. Therefore, the heat removal efficiency increases and the polymerization conversion rate also improves. In addition, since the polymerization temperature is high,
The polyethylene produced is in a molten state, and unlike gas phase polymerization or suspension polymerization, there is no need to melt it again to form pellets, which is advantageous in terms of energy.

On the other hand, the problem with polymerization under high temperature and high pressure is that the chain transfer rate is significantly higher than the growth rate of ethylene in high temperature polymerization, so the produced polymer has a sufficient melt flow index (MFB). This means that it is in the lower range. This is a particular problem when copolymerizing ethylene with an α-olefin, since the chain transfer rate of α-olefin is higher than that of ethylene, making it more difficult to lower the VFR.

The polymerization conversion rate can be improved by increasing the polymerization temperature, but on the other hand, increasing the polymerization temperature causes a decrease in MFH. Unless measures are taken to improve the polymerization conversion rate, the %A5 problem cannot be ignored.

"11S1L Summary The present invention aims to provide a solution to the above problems,
This objective is achieved by a method for the polymerization of ethylene with a combination catalyst of a specific embodiment.

Therefore, the ethylene polymerization method according to the present invention is carried out at a temperature of at least 121°C in the presence of the following catalyst components (4) to (C).
It is characterized by polymerizing ethylene or ethylene and at least one α-olefin at a temperature above and under a pressure of at least 100 KFlool.

(4) A solid catalyst component containing at least titanium, magnesium, and arsenic chlorine.

(B) Organoaluminum compound.

(Q: A ring compound having a basic skeleton represented by the following formula.

(In the formula, R2 is a hydrocarbon group, R5, R4, R5 are hydrocarbon groups, and R5, RF% R5 and R6 may be connected to each other to form a ring.

X is N or O) Effects According to the present invention, homopolymerization or copolymerization of ethylene using a specific catalyst component at a temperature of at least 0 or more and at a pressure of at least 000 Q/(32 or more) By doing this, MFR controllability is improved and low-M
It has become possible to produce FH polyethylene, and it has also become possible to improve the conversion rate by increasing the polymerization temperature.

`` ■ 對MORIRI tiga Catalyst Component Solid Catalyst Component (Catalyst Component) The solid catalyst component (A) is a solid product containing at least titanium, magnesium, and chlorine. As is clear from its definition, the solid catalyst component may contain other elements or organic compounds other than titanium, magnesium and chlorine, as long as the object of the present invention is not unduly impaired.

Methods for producing such catalyst components are already known.

In many cases, the titanium compound is present in a supported form on a magnesium compound, and the chlorine atom is
It is usually supplied from magnesium compounds. As a method for producing such a solid catalyst component,
≠7676, Special Public Sho Section 7-Hiroshi t269, Special Public Sho≠6
-3 Hiro O Octopus, Tokuko Akira! O-3 Cocoa No. 0, Tokko Akira≠
Examples include those described in Publication No. 7-≠Ori No. 52, Japanese Patent Publication No. Shosan t-54Lari, etc.

The starting magnesium compounds used in producing the melting medium component include magnesium oxide, magnesium hydroxide, dialkoxymagnesium, dialkoxymagnesium, alkoxymagnesium halide, alkoxymagnesium halide, magnesium cybaride, magnesium dicarboxylate, Examples include organomagnesium and complexes of organomagnesium and metal halides.

Examples of the starting titanium compound used in producing this catalyst component include titanium tetrahalide, titanium trihalide, alkoxytitanium halide, allyloxytitanium halide, and titanium alcoholade.

Here, the titanium compound may be not only a pure titanium compound but also a complex or mixture with a foreign compound such as metal aluminum, aluminum halide, or an electron donor.

The composition of such catalyst components includes titanium content o,
z - t z% by weight, titanium/magnesium (atomic ratio)
, is 0.0! -0, J-1 and chlorine content 30-70
% by weight is preferred.

A more preferred solid catalyst component used in the present invention (
Specific examples of A) include the following.

(1) A solid composition obtained by mixing and pulverizing magnesium dihalide, titanium trichloride, and an electron donor.

(2) Magnesium dihalide, titanium trichloride,
A solid composition obtained by mixing and grinding silicon tetrachloride and an electron donor.

(3) A solid composition obtained by adding one-liquid titanium halide to a composition containing magnesium dihalide and titanate ester.

(4) A solid composition obtained by adding methylhydrogenpolysiquaxane and liquid titanium halide to a composition containing magnesium dihalide and titanate ester.

Specific examples of the above-mentioned "electron donor" are disclosed in, for example, JP-A No. 704 and JP-A No. 20≠to44. Particularly preferred electron donors in the present invention are esters, ethers, and ketones.

Organoaluminum compound (catalyst component B) Specifically, the following (1) to (5) are used as the organoaluminum compound (B).
).

(1) Trialalkylaluminum trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, tridecylaluminum, etc.

(2) Alkylaluminum/1ride diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, etc.

(3) Alkyl aluminum hydride diethyl aluminum hydride, diisobutyl aluminum hydride, etc.

(4) Alkylaluminium alkoxides such as diethylaluminium ethoxide, diethylaluminum butoxide, diethylaluminum phenoxide, and the like.

(5) Alkylsiloxalane Examples include trimethyldimethylsiloxalane, trimethyldimethylsiloxalane, and dimethylethyldiethylsiloxalane. These alkylsiloxalanes are generally synthesized in advance by reacting triple-kill aluminum and polysiloxanes, and the two are combined in a polymerization reactor at an atomic ratio of 817 At/ −／
The organic aluminum compounds of (1) to (5) above may be used not only alone but also in combination of two or more.

Most preferred among such organoaluminum compounds are alkyl aluminum halides such as diethyl aluminum.

Heterocyclic compound (catalyst component C) The catalyst component (C) used in the present invention has the general formula (wherein,
R2 is a hydrocarbon group, R5, R', R5 and R6 are hydrogen or hydrocarbon groups, R5 and R'' and R5 and R
At least one of each of 6 is a hydrocarbon group, and R5, R4, R5 and R6 may be linked to each other to form a ring. X is N or 0. ) is a heterocyclic compound having the basic skeleton.

In the formula, R2 is preferably an alkylene group having a carbon number of λ to 1, to which a substituent such as an alkyl group, an alkoxyl group, or an acyloxyl group (all have a carbon number of up to 100%) is added. Good A.

In the formula, R5, R4, R5 and R6 are preferably all hydrocarbon groups having carbon number/-j, or are mutually bonded to form a ring having 3 to 7 carbon atoms. It is preferable to b.

Specifically, the following compounds can be exemplified.

(+), z, t-substituted piperidines CH5, ^
u(C2H)2 (3) x, a-substituted tetrahydrobilane (4) λ,
Among the 1-substituted pyrrolidines, preferred b are λ, J, j, 4-tetramethylpiperidines and cineoles.

Preparation of Catalyst The catalyst of the present invention consisting of a combination of catalyst components (A), (B) and (C) can be prepared by mixing these components all at once or in stages, or by pulverizing them if necessary. can be manufactured.

The heterocyclic compound of component (C) may be mixed in advance with component (A) and/or component (B), but it is possible to form a catalyst precursor by combining components (A) and (B). Alternatively, a method may be adopted in which a catalyst is prepared in advance and component (C) is introduced when or prior to introducing the olefin to be polymerized to form a catalyst in the coexistence of the olefin.

Quantitative ratio of catalyst components The quantitative ratio of catalyst components is Al/T1 atomic ratio/-100, preferably 3, in terms of titanium atoms in the solid component (A) and aluminum atoms in the organoaluminum compound (B).
-3 o, or -2. o, or -2. Preferably 0. /-/.

Polymerization of Ethylene The polymerization carried out using the catalyst system of the invention is a homopolymerization of ethylene or a copolymerization of ethylene with at least one α-olefin of the general formula R-CH═CH2.

Polymerization Apparatus Although the polymerization of the present invention can be carried out as a batch operation, it is common to carry out one polymerization in a continuous manner. As the polymerization apparatus, those commonly used in high-pressure radical polymerization of ethylene can be used. Variants include continuously stirred seed reactors or continuous hole tube reactors.

The polymerization can be carried out as a single-zone process using these single reactors, but it is also possible to use a number of reactors in series, or possibly with condensers, or in a multi-zone process. It is also possible to use a single reactor, the interior of which is effectively divided into several zones. The multi-zone method uses different reaction conditions in each zone to control the monomer composition in each reactor or reaction zone in order to control the properties of the polymer obtained in each reactor or zone. , the catalyst concentration, the amount of the molecular weight regulator, etc. can be adjusted. Moreover, when combining multiple reactors, various combinations can be adopted, such as a tube type and a tube type, a tank type and a tank type, and a tank type and a tube type.

The polymer produced in the reactor can be treated in the same manner as high-pressure polyethylene by separating unreacted monomers.

In addition, unreacted monomers can be re-pressurized and recycled to the reactor.

The catalyst is preferably pumped directly into the reactor as a finely divided dispersion in a suitable inert medium. Suitable inert media used here are, for example, white spirit, hydrocarbon oils, penmen, hexane,
Hydrocarbon solvents such as cyclohexane, heptane, and toluene.

Monomers and Comonomers The catalyst system of the present invention can be used to carry out the homopolymerization of ethylene. At this time, it is common to obtain high-density polyethylene having a specific gravity in the range of 3 to 0, P7. It is also possible to copolymerize ethylene with at least one α-olefin. At this time, the specific gravity is O
It is possible to obtain linear medium- to low-density polyethylene of about 30 to 000 lamps.

The method of the present invention is particularly suitable for producing the above-mentioned copolymers, and can provide medium to low density ethylene copolymers in high yield.

In the case of copolymerization, the comonomer has the general formula R-CH=CH
2 (here, R is a hydrocarbon residue having carbon number /-/2).

) is preferred, and examples of its variants include propylene, butene-7, pentene-l, hexene-l, heftene-l, octene-! , decene-1%
Examples include .mu.m methylpentene-1. These can be copolymerized with ethylene, not just one type, but also a combination of multiple types. These α-olefins are present in the produced copolymer in an amount ranging from ICO to 30% by weight.

Preferably, up to 3 to 20 weight parts can be copolymerized.

Polymerization conditions (1) Polymerization pressure The polymerization pressure used in the present invention is at least CO00
kg/II2, preferably 300-≠000 kg
Zi, more preferably zoo~3!00 kg/l;
pressure in the range of .

(2) Polymerization temperature The polymerization temperature is at least 1,2! ℃ or higher, preferably 750 to 350℃, more preferably 200 to 3 θ
within the range of ℃.

Although not essential to the present invention, depending on the combination K of polymerization pressure and polymerization temperature employed, the polymerization reaction mixture may form a single fluid phase or may form two phases. Sometimes they are separated.

Reactor feed gas composition The feed gas composition employed in the present invention is ethylene t
-too much weight, at least one α-olefinic comonomer, and hydrogen as a molecular weight regulator.
It is preferable that the molar ratio is within the range of 100 molar range.

Residence TimeThe average residence time in the reactor is related to the duration of activity of the catalyst under the reaction conditions employed. The half-life of the catalyst used is particularly influenced by the temperature among the reaction conditions, and as the life of the catalyst increases, it is preferable to increase the average residence time in the reactor by ~1°, which is adopted in the present invention. Average residence time is 2~tsoo
It is within the range of seconds, preferably within the range of 3 to 10 seconds, more preferably within the range of 10-120 seconds.

Experimental Examples Example-7 Production of solid catalyst component (A) A stainless steel pot with an internal volume of 1 liter was filled with stainless steel balls with an apparent volume of J7 m in diameter, and eroded in advance. The treated metal aluminum reduced thymene trichloride (TlCl3 (AA)) was treated as IAo, 9. 1 sotz of anhydrous magnesium chloride, /3 silicon tetrachloride
N and methyl methacrylate were sealed in a /311 nitrogen atmosphere, and the mixture was ground in a vibrating mill for 10 hours.

The Tl loading rate of this product was 4A and 27% by weight.

Hereinafter, this will be referred to as A-/.

Preparation of Catalyst Dispersion Into a 1-liter flask that was sufficiently purged with nitrogen, sufficiently degassed and purified n-heptano was introduced. The Ti/Ti atomic ratio was increased to 1. Next, sufficiently degassed and purified hexene-7 is introduced so that the molar ratio of hexene-1/T1 becomes SO.
,! Stir for hours. Furthermore, 2,2°4,A-tetramethylpiperidine (Q is the heterocyclic compound/Ti molar ratio o,
I added it so that it would be.

This catalyst suspension was placed in a catalyst preparation tank equipped with a stirrer and purged with nitrogen, and diluted with n-hebutane to a solid catalyst component preparation concentration of 0.2i/9 tt.

Ethylene and hexene-7 were copolymerized under the reaction conditions shown in Table 1 in a stirred autoclave type continuous reactor having an internal volume of high-pressure polymerization of ethylene/t liter.

The details of the results were as shown in Table-2.

Examples 2 and 3 As the heterocyclic compound of the catalyst component (C), 2,2. ! .

In place of 6-tetramethylpiperidine, ≠-penzoyloxyco, 2,6. An experiment similar to Example 1 was conducted except that t-tetramethylpiperidine and 1,r-cineole were used in preparing the catalyst dispersion.

Details of polymerization conditions and results are shown in Table 7 and Table 2, respectively.
It was a letter from VC.

Comparative Example Heterocyclic compound of catalyst component (C) 2,2. Example except that t,t-tetramethylpiperidine was not used.
An experiment similar to 1 was conducted.

Details of polymerization conditions and results are shown in Table 1 and Table λ, respectively.
The rules were as shown in .

Example-μ Production of solid catalyst component (A) 200% of n-hebutane, which had been thoroughly dehydrated and purified, was introduced into a 7-liter flask that had been purged with nitrogen.

Next, 0.1 mol of MgCl2 and 3.1 mol of AlCl3 were added. t mmol of Ti(0C4H9)II and o.mu.mol of Ti(0C4H9)II were introduced. Furthermore, Q07 mol of n-butanol was introduced, the temperature was raised to 70°C, and the mixture was stirred for 1 hour.

Next, 0.02 mol of titanium tetrachloride and 1.5 mol of methylhumanidiene polysiloxane were introduced.

The mixture was stirred for an additional hour.

After the reaction is complete, wash thoroughly with heptane to remove the solid catalyst component (A
) was obtained.

The Ti loading rate of this product was r, 1 weight.

Hereinafter, this will be referred to as A-J.

Preparation of catalyst dispersion It was carried out in the same manner as in Example-1.

ethylene polymerization It was carried out in the same manner as in Example-1.

Details of polymerization conditions and results are shown in the table below! The results were as shown in Table 1.

Comparative Example-λ Heterocyclic compound of catalyst component (C) 2,2. t, 1. An experiment similar to Example 1 was conducted except that -tetramethylpiperidine was not used.

Details of polymerization conditions and results are shown in Table 7 and Table 2, respectively. *1: Units are I, polyethylene/I, solid catalyst component + 2
:F, R, is the load at the measurement temperature of 0℃, /A
Load for MFRK of kg10. The ratio of MFH of Okg is shown.

Claims (1)

[Claims] In the presence of the following catalyst components (A) to (C), at least one
A method for polymerizing ethylene, comprising polymerizing ethylene or ethylene and at least one α-olefin at a temperature of 25° C. or higher and a pressure of 200 kg/cm^2 or higher. ￥Catalyst component￥ (A) A solid catalyst component containing at least titanium, magnesium and chlorine. (B) Organoaluminium compound. (C) A heterocyclic compound having a basic skeleton represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^2 is a hydrocarbon group, R^3, R^4, R^5
and R^6 is hydrogen or a hydrocarbon group, and at least one of R^3 and R^4 and at least one of R^5 and R^6 is a hydrocarbon group, and R^3, R^4, R
^5 and R^6 may be connected to each other to form a ring. X is N or O. )