WO2002038622A1

WO2002038622A1 - PREPOLYMERIZATION METHOD OF α-OLEFIN

Info

Publication number: WO2002038622A1
Application number: PCT/KR2001/001757
Authority: WO
Inventors: Woo-Kyoung Kim; Kun Lo; Il-Seop Kim
Original assignee: Samsung General Chemicals Co Ltd
Current assignee: Hanwha Impact Corp
Priority date: 2000-11-09
Filing date: 2001-10-18
Publication date: 2002-05-16
Anticipated expiration: 2003-05-09
Also published as: KR20020036286A; JP2004513991A; EP1339759A4; EP1339759A1; CN1478100A; CN1210311C; KR100389961B1; WO2002038622A8

Abstract

The present invention relates to a method for the prepolymerization of α-olefin in the presence of a catalyst system which comprises (a) a magnesium supported solid complex titanium catalyst and (b) an organometallic compound of metal of Group I or III of the Periodic Table, characterized in that an inert solvent having high viscosity with molecular weight of 300g/mole or more is used as a reaction medium.

Description

PREPOLYMERIZATION METHOD of α-OLEFIN

TECHNICAL FILED

The present invention relates to a method for the prepolymerization of α

-olefin in the presence of (a) a magnesium supported solid complex titanium catalyst

and (b) an organometallic compound of metal of Group I or III of the Periodic Table,

characterized in that an inert solvent having high viscosity with molecular weight of

300 g/mole or more is used as a reaction medium.

The present invention relates to a prepolymerization method which can be

used in the uniform feeding of prepolymers with large diameter into a reactor, and

thereby the present invention is useful when there is non-uniformity in concentration

caused by precipitation of prepolymer due to its particle's large diameter, e.g, 100

μm or more, and when there is a plugging in a high pressure pump when it is fed into

a small scale reactor such as in pilot scale.

DISCLOSURE OF INVENTION

The prepolymerization of α-olefin was conventionally conducted at room

temperature using an inert liquid solvent with low molecular weight (lOOg/mole or

less) and low viscosity such as hexane and heptane as a reaction medium, and then

the α-olefin prepolymer was fed in the reactor by using a pump after diluted into a

slurry state in the storage drum. In this process, when the α-olefin prepolymer has a

large diameter (100 μm or more), it precipitates within the storage drum and thereby varying its concentration within the storage drum as the feeding time elapses. Further,

when a commercial quantitative pump, which is typically in use for feeding a small

amount of α-olefin prepolymer into a small scale reactor such as in pilot scale, is

used, it induces a frequent abnormal feeding, because of its particle's large diameter

e.g. lOOjMii or more.

The present invention is directed to solve the above mentioned problems,

and the purposes of the present invention are to provide a prepolymerization method

of α-olefin which is capable of preventing abnormal feeding and improving reaction

uniformity by conducting the reaction within a reaction medium with molecular

weight of 300g/mole or more and high viscosity such as mineral oil.

The prepolymerization method of α-olefin according to the present

invention, which is conducted in the presence of a catalyst system which comprises

(a) a magnesium supported solid complex titanium catalyst and (b) an organometallic

compounds of metal of Group I or III of the Periodic Table, is characterized in that

an inert solvent having high viscosity with molecular weight of 300g/mole or more is

used as a reaction medium. Mineral oil is especially preferred as a reaction medium.

The magnesium supported solid titanium catalyst (a) used in the present

invention may be a typical Zieglar-Natta type catalyst described in U.S Patent Nos.

4,482,687, 4,277372, 3,642,746, 3,642,772, 4,158,642, 4,148,756, 4,477,639,

4,518,706, 4,946,816, 4,866,022, 5,013,702, 5,124,297, 4,330,649, European Patent

No. 131,832 or Japanese Patent Publication No. Sho 63-54004, etc. A preferable example of the magnesium supported solid titanium catalyst (a)

used in the present invention is a catalyst prepared by a simple and efficient

preparation method, which is, comprises the following steps:

(i) preparing a solution containing magnesium by dissolving a magnesium

compound having no reducibility such as magnesium halide and a Group II-IA

compound of the Periodic Table into the solvent mixture of cyclic ether, one or more

of alcohol, a phosphorus compound and organosilane;

(ii) precipitating solid particles by reacting said solution containing

magnesium with a transition metal compound, a silicone compound, a tin compound

or the mixture thereof; and then

(iii) reacting said precipitated solid particles with a titanium compound and

an electron donor, and then obtaining solid catalyst particles having regulated shapes

after washing said reaction product with hydrocarbon solvents.

Preferable examples of the organometallic compound (b) used in the present

invention include one or more compounds selected from the group consisting of

trialkylaluminium such as triethylaluminium or tributylaluminium,

trialkenylaluminium such as triisoprenylaluminium, partially alkoxylated

alkyaluminium including dialkylaluminiumalkoxide such as

diethylaluminiumethoxide or dibutyaluminiumbutoxide and

alkylaluminiumsequialkoxide such as ethylaluminiumsequiethoxide or

butyaluminiumsequiethoxide, partially halogenated aluminium including

alkylaluminiumdihalide such as ethylalumniumdichloride, propylaluminiumdichloride or butylaluminiumbromide, dialkyaluminiumhydride

such as diethylaluminiumhydride or dibutylaluminiumhydride and partially

alkoxylated halogenated alkylaluminium such as ethylaluminiumethoxychloride,

butylaluminiumbutoxychloride or ethylalurmniumethoxybromide, more preferably,

trialkylaluminium.

An inert solvent with comparably low viscosity such as hexane, heptane and

kerocene is typically used as a reaction medium when the prepolymerization is

conducted in the liquid state, but in the present invention an inert solvent, especially

with molecular weight of 300g/mole or more and comparably high viscosity is used

as a reaction medium, thus the phenomenon in which prepolymers precipitate after

the completion of prepolymerization can be suppressed. The viscosity range of the

inert solvent used in the present invention is desirably 50 to lOOcst (centistokes) at

40 TJ .

Further, in the present invention, when the prepolymer is fed into the

reaction vessel, it is uniformly mixed with grease having high viscosity with

appropriate ratio so that the prepolymers could not precipitate even in the long-term

storage, and then said uniformly mixed mixture with high viscosity is uniformly fed

into the reaction vessel by using a metering pump appropriate for fluid with high

viscosity. Thus, the abnormal feeding into the reaction vessel can be avoided, then

reaction uniformity can be improved, and also the prepolymers can be uniformly

distributed without being precipitated.

For the prepolymerization in the liquid state according to the present invention, a desirable ratio of the solid complex titanium catalyst (a) is titanium atom

of about 5 to 500 mmole, preferably about 10 to 100 mmole on the basis of 1 liter of

the inert solvent, a desirable ratio of organometal, especially aluminium atom, in the

organometallic compound (b) component is about 0J to 100 moles, preferably about

0.5 to 50 moles on the basis of titanium atom of 1 mole in the catalyst (a).

The prepolymerization method of α-olefin of the present invention proceeds

in the same manner as the prepolymerization method of olefin using conventional

Ziegler-type catalysts. Especially, the prepolymerization is conducted in the absence

of oxygen and water. In the prepolymerization of the present invention using an inert

solvent with molecular weight of 300g/mole or more and high viscosity as a reaction

medium, the reaction conditions should be selected after considering the liquid

viscosity of said inert solvent and the solubility of α-olefins to the reaction medium,

etc. The prepolymerization temperature is preferably about 10 to 100 °C , more

preferably about 30 to 80 ^°C . Pressure is preferably about 50 atm or less, more

preferably about 0J to 10 atm. The time for the prepolymerization is determined

after considering the desirable degree of the prepolymerization, catalyst activity and

solubility of α-olefins, etc., preferably, 30 minutes to 5 hours.

According to the α-olefin prepolymerization method of the present

invention, the concentration uniformity and feeding stability of the slurry of a

catalyst with a large diameter of 100 jwn or more and, thereby the polymerization

stability of the polymerization reaction and quality uniformity of the final product may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the feed uniformity and the change in temperature of the

reactor according to one preferred example of the α-olefin prepolymerization

method of the present invention.

BESTMODEFORCARRYINGOUT THEINVENTION

The present invention is described in detail according to the examples and

comparative examples, but the scope of the present invention is not limited by these

examples and comparative examples.

Example 1

Prior to the prepolymerization, mineral oil to be used herein was added to a

flask, and heated to 100 °C while it was agitated for 12 hours or more in a nitrogen

atmosphere in order to remove moistures contained in the mineral oil. A 4-liter

polymerization reactor equipped with a mechanical agitator and a cooling/heating

jacket was prepared into the nitrogen atmospheric condition, and then 1,300ml of

mineral oil as a reaction medium, lOOg of titanium catalyst and 150mmol of

triethylaluminium were fed into the reactor in sequence. The reaction temperature

was raised to 40 °C while the reaction medium was agitated at 350rpm. After the

reaction medium was agitated for about 30 minutes, propylene was fed thereto. The

prepolymerization was conducted, while the reaction temperature was maintained at 0 °C and the propylene was fed in at the flow rate of 2g/min for 2.5 hours.

Example 2

The precipitation level was compared with respect to three types of slurries

as follows:

Sample 1: Prepolymer slurry in oil prepared in Example 1 + grease

(oil/grease =2/1 weight ratio).

Sample 2: Prepolymer slurry in oil prepared in Example 1 + grease

(oil/grease =3/1 weight ratio).

Sample 3: (comparative example) Prepolymer slurry in hexane.

(1) For the above three samples, the degree of prepolymerization was 3

(g-PP/g-catalyst), and the concentration was 20 weight percent.

(2) The above three samples were respectively added into a glass bottle with

7cm of diameter to 100mm height while the samples were uniformly agitated.

(3) Each of the bottles containing the slurry samples was uniformly mixed,

and then the precipitation depth was measured as a function according to the time

after it was left in a vessel at 0 ^°C .

Table 1. Comparison of precipitation depth by types of solvents and as a

function to the time (unit: mm)

Table 1 shows that there was no precipitation until 5 days when the

prepolymer slurry in oil and grease were mixed, but most of the prepolymer slurry in

the hexane slurry was precipitated within 5 minutes.

Example 3

The feeding stability in a continuous polypropylene polymerization reactor

in a pilot scale was compared with those of the prepolymer prepared in the same

manner as the composition of the prepolymer slurry in oil + grease mixture

(oil/grease = 2/1 weight ratio) experimented in the above EXAMPLE 2 and the

prepolymer slurry in hexane.

(1) 30kg of liquid propylene was added to a 150 Liter polymerization reactor

equipped with an agitator.

(2) The reaction temperature was controlled to 67 ^°C , and hydrogen was fed

thereto until the pressure rose to 30kg/cm².

(3) The prepolymer was fed at the amount of lg-titanium per 1 hour, and the

triethylaluminium was continuously fed thereto until the ratio of aluminium to

titanium atom (g-aluminium/g-titanium) became 4, and also the Si-type electron

donor was continuously fed thereto until the ratio of silicone to titanium atom

(g-silicone/g-titanium) became 3.5.

(4) The prepolymer slurry in oil + grease mixture was fed into the reactor by using a piston-type pump, and the prepolymer slurry in hexane was fed into the

reactor by using a reciprocating metering pump.

(5) The feeding uniformity and the change in temperature of the reactor in

the two above cases were measured, and the results are shown in Fig 1.

Fig. 1 shows that the feeding rate was not uniform and thereby the reaction

temperature severely fluctuated in the case of feeding the prepolymer slurry in

hexane into the reactor, while the feeding rate was uniform and thereby the reaction

temperature was relatively uniform in the case of feeding the'prepolymer slurry in oil

plus grease into the reactor.

In conclusion, the phenomena, in which the prepolymers become

precipitated after the completion of prepolymerization, was reflectively suppressed,

and thereby the abnormal feeding was prevented, and the uniformity of the reaction

was improved by using the prepolymerization method according to the present

invention.

Claims

WHAT IS CLAIMED IS;

1. A prepolymerization method of α-olefin in the presence of a catalyst system

which comprises (a) a magnesium supported solid complex titanium catalyst and (b)

an organometallic compound of metal of Group I or III of the Periodic Table,

wherein an inert solvent of high viscosity with molecular weight of 300g/mole or

more is used as a reaction medium.

2. The method of Claim 1, wherein the inert solvent is mineral oil.

3. The method of Claim 1, wherein the viscosity of said inert solvent is in the range

of 50 to 100 centistokes at 40 ^°C .

4. The method of any one of Claims 1 to 3, wherein said organometallic compound is

trialkylaluminium.

5. The method of any one of Claims 1 to 3, wherein the ratio of said solid complex

titanium catalyst (a) to the inert solvent is 5 to 500 millimoles of titanium atoms per

one liter of the inert solvent, and the ratio of organometals in the organometallic

compound (b) component to the catalyst (a) is 0J to 100 moles per one mole of

titanium atoms in the catalyst (a).