Method for operating reactor for polymerizing olefins

In the preparation of polyolefin in a vapor phase polymerization using catalysts comprising a solid catalyst component containing titanium and/or vanadium; and magnesium and an organoaluminum compound, when the reaction is stopped for a certain period of time, the restarting of reaction is possible by feeding in the first place an organoaluminum compound into the reaction system with retaining of polymer particles in the reactor.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
This invention relates to a method for operating the reactor for producing 
polyolefins through a vapor phase polymerization method. More 
particularly, the invention relates to a method for restarting the 
operation after the interruption of reaction in the preparation of 
polyolefins through vapor phase polymerization. 
2. Description of Prior Art 
The vapor phase polymerization method of olefins to prepare a polyolefin is 
widely employed for the reason that its production cost is low. The system 
for the vapor phase polymerization is exemplified by a fluidized bed 
system or a stirred bed system. (cf. British Patent Nos. 1,248,951, 
1,248,952, and 1,248,953; U.S. Pat. No. 3,971,768). 
In the vapor phase polymerization to prepare polyolefins, various kinds of 
serious situations happen to occur to interrupt the operation of the 
reactor due to several troubles or remedy work of equipment. For example, 
troubles are often caused to occur in the steps of powder treatment, 
pelletizing and blending subsequent to the polymerization step, or in the 
cases that temporary storage tanks are filled up with produced polymer 
particles or a gas blower for recycling is out of order. In these 
troubles, the polymerization process is stopped not completely but 
temporarily and, after the remedy of a trouble, the operation is restarted 
without delay. 
For stopping the reaction, a deactivator is sometimes introduced into a 
reaction system. However, under some other operation conditions, the 
deactivator is not used so as to avoid undesirable influences that are 
caused by the deactivator. The term "deactivator" used herein is intended 
to mean an agent that interrupts a polymerization reaction proceeding at 
some stage. 
Without the use of deactivator, the reaction can be temporarily stopped and 
started again by the following methods. 
(1) The feeds of a solid catalyst component and an organoaluminum compound 
is discontinued and the feeds of gases including olefin are reduced in 
proportion to the lowering of the rate of reaction. After the rate of 
reaction is lowered to a certain level such as to a half or a third of the 
regular reaction rate, all the feeds of reactant gases are stopped. 
(2) The feeds of all gases are stopped simultaneously with the stopping of 
feeds of solid catalyst component and organoaluminum compound and the 
pressure and temperature are lowered. 
In any stopping process, the pressure and temperature are lowered and gases 
in the reaction system are purged with an inert gas, and the polyolefin 
particles remaining in the reaction vessel are discharged. 
The reason for the discharge of polyolefin particles is as follows. The 
concentrations of the solid catalyst component and organoaluminum compound 
in the remained polymer particles vary in each stopping operation. If the 
operation is restarted with the remained polymer as it stands, the 
conditions to start reaction are not settled and vigorous reaction is 
sometimes caused to occur in the initial stage of reaction or, to the 
contrary, the starting of reaction takes many hours. In addition, as 
described later on, the trouble due to the formation of sheet-like polymer 
is liable to occur. 
Accordingly, the restarting may be carried out after feeding the reaction 
vessel with new polyolefin particles. 
The method for emergency stop by introducing a deactivator into a reaction 
system and its restarting are as follows. 
The polymerization reaction is stopped by feeding a deactivator such as 
carbon monoxide gas or carbon dioxide gas into a reaction vessel (cf. EP-A 
No. 136029), which is followed by the purging of gases in the reaction 
system with an inert gas such as nitrogen. After that, the polyolefin 
particles remaining in the reaction vessel is discharged. 
The mechanism to stop the reaction using a deactivator is such that the 
reaction between a deactivator and a catalyst or co-catalyst is firstly 
caused to occur and, as a result, the catalyst loses its function to stop 
the reaction. The reaction between a deactivator and a catalyst or 
co-catalyst is analyzed to some extent, however, the influences of its 
reaction products on the polymerization reaction has not been clarified 
sufficiently. In addition, there is similar apprehension when a 
deactivator is allowed to remain in the reaction system. 
Accordingly, it has been a usual practice that the reaction is stopped by a 
deactivator as described above, and when the reaction is started again, 
not only a deactivator and gases including reactant gases but also 
polyolefin particles remaining in the reaction system are all discharged 
substantially. After that, polyolefin particles are newly fed into the 
reaction system and reactant gases and catalysts are then supplied so as 
to restart the operation. 
In this method as described above, the preparation is usually restarted by 
the following method. The polyolefin particles remaining in a reaction 
vessel are discharged and the polyolefin particles produced in a regular 
state or those produced in a separate process are introduced into the 
reaction vessel, the space within the reaction system is subjected to 
inert gas purging, and the operation of reaction is started again. In this 
method, however, all the contents in the reaction system are changed in 
order to restart, which is not different from the operation of newly 
starting a reaction. 
Furthermore, the fact that the troubles due to the sheet-like polymer is 
liable to occur in the initial stage of vapor phase polymerization of 
polyolefin, has already been disclosed (EP-A Nos. 224479, 313087, 315192, 
and 366823). Accordingly, various troubles due to the formation of 
sheet-like polymer are caused to occur also in the initial stage of the 
restarting operation. 
As described above, when the vapor phase polymerization of polyolefins is 
urgently stopped with or without a deactivator and the operation of the 
reactor is started again, there have been several disadvantages as follows 
in the conventional method: 
(1) The sheet-like polymer is liable to be formed in the initial period of 
the operation of reactor for polyolefin. The stopping of operation is 
unavoidable due to the blocking of pipings and valves with the sheet-like 
polymer. 
(2) When the operation is restarted, the feed quantity of catalysts is 
gradually increased to raise the rate of formation of polyolefin. 
Accordingly, temporary non-regular conditions are-continued during which 
period a wide specification material is produced. 
(3) The reactor must be exposed to the air when the polyolefin particles 
are discharged or new polyolefin particles are fed. In such an operation, 
impurities such as moisture and oxygen are liable to be introduced into 
the reaction system. Therefore, the polymerization reaction is hardly 
started in the restarting operation necessitating a long time to attain 
regular operation. This phenomenon is severe when the reaction system is 
exposed to the air for a long period of time. 
Accordingly, it is eagerly wanted to improve the restarting operation after 
the temporary stopping of the reactor for producing polyolefin. 
BRIEF SUMMARY OF THE INVENTION 
The object of the present invention is, therefore, to provide a novel and 
improved method for operating a reactor for polymerizing olefins. 
In view of the above object, the inventors of the present invention have 
carried out extensive investigations. As a result, the present invention 
has been accomplished with the finding of the facts that the restarting of 
operation for polymerization can be easily carried out by substantially 
stopping the reaction with or without the use of a deactivator, and 
retaining the polymer particles in the reaction vessel without discharging 
them, and feeding an organoaluminum compound. 
According to the present invention, in the method for operating the olefin 
polymerization reactor comprising the steps of feeding a solid catalyst 
component containing at least titanium and/or vanadium; and magnesium and 
an organoaluminum compound into a reaction vessel, polymerizing or 
copolymerizing olefins under vapor phase regular conditions, stopping the 
polymerization reaction and then restarting the operation of the reaction; 
the improvement in the stopping and the restarting of the operation which 
comprises the steps of performing all the operations to be done from the 
stopping of reaction to the restarting of reaction with retaining the 
remaining polymer particles in the reactor without discharging them after 
the stopping of reaction and feeding an organoaluminum compound to restart 
the polymerization.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention will be described in more detail in the following. 
The starting olefins used in the present invention have 2 to 8 carbon 
atoms, preferably 2 to 6 carbon atoms. For example, .alpha.-olefins such 
as ethylene, propylene, butene-1, pentene-1, hexene-1, and 
4-methylpentene-1 are used. These olefins can be used singly for 
homopolymerization or for copolymerization of two or more kinds of them. 
The combinations of monomers for copolymerization are exemplified by those 
of ethylene and an .alpha.-olefin having 3 to 12 carbon atoms such as 
ethylene/propylene, ethylene/butene-1, ethylene/hexene-1, and 
ethylene/4-methylpentene-1; propylene/butene-1; and the combination of 
ethylene and two kinds or more of .alpha.-olefins. 
Furthermore, it is possible to copolymerize with dienes for the purpose to 
improve the properties of polyolefin. Exemplified as the dienes are 
butadiene, 1,4-hexadiene, ethylidenenorbornene, and dicyclopentadiene. 
The feeding of olefins into the reaction system is preferably carried out 
together with a suitable inert carrier gas such as nitrogen. 
The catalysts used for the above polymerization of olefins are composed of 
a solid catalyst component which contains at least one or both of titanium 
and vanadium, and magnesium; and an organoaluminum compound. The solid 
catalyst component containing at least titanium and/or vanadium; and 
magnesium is exemplified by the one containing titanium and magnesium 
which is well known as a Ziegler type catalyst used for the polymerization 
of olefins, the one containing vanadium and magnesium, and the other one 
containing titanium, vanadium and magnesium. 
However, when carbon dioxide gas is introduced into a reactor in order to 
stop the reaction, it is not preferable to lose the catalytic activity of 
such a solid catalyst component by the addition of carbon dioxide to 
substantially lower the polymerization activity. In this occasion, it is 
desirable that the lowering of polymerization activity is previously 
checked by a preliminary experiment using a solid catalyst component which 
has been exposed to carbon dioxide, thereby confirming the influence of 
carbon dioxide on the solid catalyst component. 
The above catalyst components are prepared by adding a titanium compound 
and/or vanadium compound on a carrier of magnesium-containing inorganic 
solid compounds such as metallic magnesium, magnesium hydroxide, magnesium 
carbonate, magnesium oxide, and magnesium chloride, or double salts, 
double oxides, carbonates, chlorides and hydroxides containing magnesium 
and an element selected from silicon, aluminum, and calcium, or those 
obtained by treating or reacting the above inorganic solid compounds with 
an oxygen-containing compound, sulfur-containing compound, aromatic 
hydrocarbon or halogen-containing compound. 
The above-mentioned oxygen-containing compounds are exemplified by water; 
polysiloxane; organic oxygen-containing compounds such as alcohols, 
phenols, ketones, aldehydes, carboxylic acids, esters, and acid amides; 
alkoxides of metals; and inorganic oxygen-containing compounds such as 
oxychlorides of metals. The sulfur containing compounds are exemplified by 
organic sulfur-containing compounds such as thiols and thioethers and 
inorganic sulfur-containing compounds such as sulfur dioxide, sulfur 
trioxide, and sulfuric acid. The aromatic hydrocarbons are exemplified by 
monocyclic or polycyclic aromatic hydrocarbons such as benzene, toluene, 
xylene, anthracene, and phenanthrene. The halogen-containing compounds are 
exemplified by chlorine, hydrogen chloride, metal chlorides, and organic 
halides. 
The foregoing titanium compounds are exemplified by halides, alkoxy 
halides, alkoxides, and oxychlorides of titanium. Among them, tetra-valent 
titanium compounds and tri-valent titanium compounds are preferably used. 
The tetra-valent titanium compounds are represented by the general formula 
: 
EQU Ti(OR).sub.n X.sub.4-n 
in which R is a hydrocarbon radical such as an alkyl group, aryl group or 
aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and n is a 
numeral of 0&lt;n&lt;4. 
More particularly, the titanium compounds are exemplified by titanium 
tetrachloride, titanium tetrabromide, titanium tetraiodide, 
trichlorotitanium monomethoxide, dichlorotitanium dimethoxide, 
monochlorotitanium trimethoxide, titanium tetramethoxide, 
trichlorotitanium monoethoxide, dichlorotitanium diethoxide, 
monochlorotitanium triethoxide, titanium tetraethoxide, trichlorotitanium 
monoisopropoxide, dichlorotitanium diisopropoxide, monochlorotitanium 
triisopropoxide, titanium tetraisopropoxide, trichlorotitanium 
monobutoxide, dichlorotitanium dibutoxide, monochlorotitanium tributoxide, 
titanium tetrabutoxide, trichlorotitanium monopentoxide, trichlorotitanium 
monophenoxide, dichlorotitanium diphenoxide, monochlorotitanium 
triphenoxide, and titanium tetraphenoxide. 
The tri-valent titanium compounds are exemplified by the compounds which 
are prepared by reducing tetra-valent halogenated titanium alkoxides with 
hydrogen, aluminum, titanium or organometallic compounds of the group I to 
III of the periodic table. The above tetravalent halogenated titanium 
alkoxides are represented by the general formula: 
EQU Ti(OR).sub.m X.sub.4-m 
in which R is a hydrocarbon radical such as an alkyl group, aryl group or 
aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and m is a 
numeral of 0&lt;m&lt;4. 
Among the above titanium compounds, the tetravalent titanium compounds are 
preferable. 
More particularly, the catalysts are exemplified by those prepared by 
combining organoaluminum compounds with solid catalyst components of: 
MgO--RX--TiCl.sub.4 (U.S. Pat. No. 4,065,611), Mg-SiCl.sub.4 
--ROH--TiCl.sub.4, 
MgCl.sub.2 --Al(OR).sub.3 --TiCl.sub.4 (U.S. Pat. No. 4,202,953), 
MgCl.sub.2 --SiCl.sub.4 --ROH-TiCl.sub.4 (U.S. Pat. Nos. 4,006,101 and 
4,083,802), 
Mg(OOCR).sub.2 --Al(OR).sub.3 --TiCl.sub.4 (U.S. Pat. No. 4,022,958), 
Mg--POCl.sub.3 --TiCl.sub.4, MgCl.sub.2 --AlOCl--TiCl.sub.4 (U.S. Pat. No. 
4,061,857), 
and MgCl.sub.2 --Al(OR).sub.n X.sub.3 --n--Si(OR').sub.m X.sub.4-m 
--TiCl.sub.4 (U.S. Pat. No. 4,507,448) 
in which R and R' are organic residual groups and X is a halogen atom. 
The foregoing vanadium compounds are exemplified by tetra-valent vanadium 
compounds such as vanadium tetrachloride, vanadium tetrabromide, and 
vanadium tetraiodide; and penta-valent vanadium compounds such as vanadium 
oxytrichloride and orthoalkyl vanadate; and tri-valent vanadium compounds 
such as vanadium trichloride and vanadium triethoxide. 
The vanadium compounds can be used singly or in combination with the 
titanium compounds. 
Exemplified as other catalysts are the combination of organoaluminum 
compounds with a solid catalyst component prepared by reacting an 
organomagnesium compound of the so-called Grignard reagent with a titanium 
compound and/or a vanadium compound. The organomagnesium compounds are 
exemplified by the compounds represented by the general formulae: RMgX, 
R.sub.2 Mg and RMg(OR), in which R is an organic radical having 1 to 20 
carbon atoms and X is a halogen atom, and their ether complexes, and other 
compounds which are prepared by modifying the above organomagnesium 
compounds with other organometallic compounds such as organosodium, 
organolithium, organopotassium, organoboron and organocalcium. 
Typical examples of the above catalysts are the compounds prepared by 
combining an organoaluminum compound with a solid catalyst component such 
as RMgX-TiCl.sub.4 type, RMgX-phenol-TiCl.sub.4 type, RMgX-halogenated 
phenol-TiCl.sub.4 type, and RMgX-CO.sub.2 --TiCl.sub.4 type. 
Other catalyst systems are exemplified by the combination of an 
organoaluminum compound with a solid substance which is obtained by 
reacting an inorganic oxide as a solid catalyst component such as 
SiO.sub.2, Al.sub.2 O.sub.3 and SiO.sub.2 .multidot.Al.sub.2 O.sub.3 with 
the above-described solid catalyst component containing magnesium and 
titanium and/or vanadium. Besides the above inorganic oxides of SiO.sub.2, 
Al.sub.2 O.sub.3 and SiO.sub.2 .multidot.Al.sub.2 O.sub.3 ; CaO, Ba.sub.2 
O.sub.3 and SnO.sub.2 are also used. Furthermore, the double oxides of the 
above oxides can also be used. These inorganic oxides are brought into 
contact with the solid catalyst component containing magnesium and 
titanium and/or vanadium through a well-known method. More particularly, 
the reaction is carried out at a temperature in the range of 20.degree. to 
400.degree. C., preferably 50.degree. to 300.degree. C., generally for 5 
minutes to 20 hours with or without an organic solvent such as an inert 
hydrocarbon, alcohol, phenol, ether, ketone, ester, amine, nitrile or a 
mixture of them. The reaction may be carried out by any suitable method 
such as performing ball milling of all component materials. 
Practical examples of the above catalyst systems are combinations of 
organoaluminum compounds with the solid catalyst component exemplified as 
follows: 
SiO.sub.2 --ROH--MgCl.sub.2 --TiCl.sub.4 (U.S. Pat. No. 4,315,999), 
SiO.sub.2 --ROR'--MgO--AlCl.sub.3 --TiCl.sub.4 (British Patent No. 
2,099,004), 
SiO.sub.2 --MgCl.sub.2 --Al(OR).sub.3 --TiCl.sub.4 --Si(OR').sub.4 (U.S. 
Pat. No. 4,396,534), 
SiO.sub.2 --TiCl.sub.4 --R.sub.n AlCl.sub.3-n --MgCl.sub.2 --Al(OR').sub.n 
Cl.sub.3-n (EP-A No. 407143), 
SiO.sub.2 --TiCl.sub.4 --R.sub.n AlX.sub.3-n --MgCl.sub.2 --Al(OR').sub.n 
Cl.sub.3-n --Si(OR").sub.n Cl.sub.4-n (EP-A No. 413469), 
SiO.sub.2 --MgCl.sub.2 --Al(OR').sub.n Cl.sub.3-n --Ti(OR").sub.4 --R.sub.n 
AlCl.sub.3-n (EP-A No. 428375) 
SiO.sub.2 --MgCl.sub.2 --Al(OR').sub.n Cl.sub.3-n --Ti(OR").sub.n 
Cl.sub.4-n --R.sub.n AlCl.sub.3-n (EP-A No. 428375) 
SiO.sub.2 --TiCl.sub.4 --R.sub.n AlCl.sub.3-n --MgCl.sub.2 --Al(OR').sub.n 
Cl.sub.3-n --R".sub.m Si(OR'") .sub.n X.sub.4 --(m+n) (EP-A No. 493118) 
SiO.sub.2 --R.sub.n MgX.sub.2-n --Al(OR').sub.n Cl.sub.3-n --Ti(OR").sub.n 
Cl.sub.4-n --R'"OH --R.sub.n AlX.sub.3-n (EP-A No. 507574) 
SiO.sub.2 --MgCl.sub.2 --Al(OR').sub.n Cl.sub.3-n --Ti(OR").sub.n 
Cl.sub.4-n --R'"OH--R.sub.n AlCl.sub.3-n --Al(OR').sub.n Cl.sub.3-n (EP-A 
No. 500392) 
in which R, R', R" and R'" are hydrocarbon residual groups, respectively. 
In these catalyst systems, the compounds of titanium and/or vanadium can be 
used as adducts of organic carboxylic esters. Furthermore, it is possible 
to use the foregoing inorganic solid compounds after bringing the 
compounds into contact with organic carboxylic acid esters. Still further, 
the organoaluminum compounds can be used as an adduct with an organic 
carboxylic acid ester. In other words, the catalyst systems which are 
prepared in the presence of organic carboxylic acid esters can be used. 
The organic carboxylic acid esters used herein are exemplified by the 
esters of aliphatic, alicyclic and aromatic carboxylic acids. Among all, 
aromatic carboxylic acid esters having 7 to 12 carbon atoms are 
preferable, which are exemplified by alkyl esters such as methyl ester and 
ethyl ester of benzoic acid, anisic acid, and toluic acid. 
The organoaluminum compounds used together with the above-described solid 
catalyst components are those having at least one of aluminum-carbon atom 
bond in the molecule. 
For example, they are exemplified by: 
(i) organoaluminum compounds represented by the general formula: 
EQU R.sub.m Al(OR').sub.n H.sub.p X.sub.q 
in which each of R and R' is a hydrocarbon group having 1 to 15 carbon 
atoms, preferably 1 to 4 carbon atoms such as alkyl, aryl, alkenyl, or 
cycloalkyl group. The alkyl groups are exemplified by methyl, ethyl, 
propyl, isopropyl, isobutyl, sec-butyl, tert-butyl, hexyl and octyl 
groups. R and R' may be either the same or different ones. X is a halogen 
atom. The symbols m, n, p and q are, respectively, 0&lt;m&lt;3, 0&lt;n&lt;3, 0&lt;p&lt;3, 
and 0&lt;q&lt;3 as well as (m+n+p+q)=3, and 
(ii) alkylated complexes of a metal of the group I of the periodic table 
with aluminum which is represented by the general formula: 
EQU MAlR.sub.4 
in which M is a metal selected from the group of Li, Na and K, and R is the 
same hydrocarbon group as the above one. 
Exemplified as the organoaluminum compounds belonging to the above (i) are: 
EQU General formula: R.sub.m Al(OR').sub.3-m 
in which each of R and R' is the same hydrocarbon group as the above one 
and m is a numeral preferably in the range of 1.5&lt;m&lt;3. 
EQU General formula: R.sub.m AlX.sub.3-m 
in which R is the same hydrocarbon group as the above one, X is a halogen 
atom and m is a numeral preferably in the range of 0&lt;m&lt;3. 
EQU General formula: R.sub.m AlH.sub.3-m 
in which R is the same hydrocarbon group as the above one and m is a 
numeral preferably in the range of 2&lt;m&lt;3. 
EQU General formula: R.sub.m Al(OR').sub.n X.sub.q 
in which R is the same hydrocarbon group as the above one, X is a halogen 
atom, and each of m, n and q is a numeral preferably in the ranges of 
0&lt;m&lt;3, 0&lt;n&lt;3, and 0&lt;q&lt;3 and (m+n+q)=3. 
The organoaluminum compounds belonging to the group (i) are exemplified by 
trialkylaluminums such as trimethylaluminum, triethylaluminum, 
triisopropylaluminum, triisobutylaluminum, tri-sec-butylaluminum, 
tri-tert-butyl aluminum, trihexylaluminum and trioctylaluminum; 
trialkenylaluminum; dialkylaluminum alkoxides such as diethylaluminum 
ethoxide and dibutylaluminum butoxide; alkylaluminum sesquialkoxide such 
as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide as well 
as partially alkoxylated alkylaluminum represented by the average 
composition of R.sub.2.5 Al(OR).sub.0.5 ; dialkylaluminum halides such as 
diethylaluminum chloride, dibutylaluminum chloride, and diethylaluminum 
bromide; partially halogenated alkylaluminums such as ethylaluminum 
sesquichloride, butylaluminum sesquichloride, ethylaluminum sesquibromide; 
partially hydrogenated alkylaluminums such as dialkylaluminum hydrides of 
diethylaluminum hydride and dibutylaluminum hydride and alkylaluminum 
dihydrides such as ethylaluminum dihydride and propylaluminum dihydride; 
and partially alkoxylated and halogenated alkylaluminums such as 
ethylaluminum ethoxychloride, butylaluminum butoxychloride, and 
ethylaluminum ethoxybromide. 
The organoaluminum compounds belonging to the above group (ii) are 
exemplified by LiAl(C.sub.2 H.sub.5).sub.4 and LiAl(C.sub.7 
H.sub.15).sub.4. 
As the above organoaluminum compounds belonging to the above (i), it is 
possible to use the compounds in which two or more aluminum atoms are 
bonded through oxygen atoms or nitrogen atoms can also be used, which 
compounds are exemplified by (C.sub.2 H.sub.5).sub.2 AlOAl(C.sub.2 
H.sub.5).sub.2, (C.sub.4 H.sub.9).sub.2 AlOAl(C.sub.4 H.sub.9).sub.2, and 
(C.sub.2 H.sub.5).sub.2 AlN(C.sub.2 H.sub.5)Al(C.sub.2 H.sub.5).sub.2. 
Among the above-mentioned compounds, trialkylaluminums are most preferable. 
The quantity of organoaluminum compound to be used in regular operation is 
not limited, however, it may be in the range from 0.05 to 1000 moles per 1 
mole of titanium compound. 
The polymerization according to the present invention is carried out in 
like manner as the ordinary polymerization of olefins in the presence of a 
Ziegler type catalyst. That is, the reaction is carried out substantially 
under a vapor phase condition. 
Concerning other polymerization conditions, the temperature is in the range 
of 10.degree. to 200.degree. C., preferably 40.degree. to 150.degree. C. 
and the pressure is in the range from the atmospheric pressure to 70 
kg/cm.sup.2 .multidot.G, preferably 2 to 60 kg/cm.sup.2 .multidot.G. 
The regulation of molecular weight can be attained effectively by adding 
hydrogen into a polymerization system although it can be done to some 
extent by changing the polymerization conditions such as temperature, 
molar ratios of catalysts or the like. 
Furthermore, the reactor for the vapor phase polymerization or 
copolymerization of olefins includes all the apparatus in fluidized bed 
system which are substantially operated under a vapor-solid phase system. 
The installation of a stirrer for a reactor is optional. 
In a regular operation, an olefin or olefins, solid catalyst component and 
organoaluminum compound are constantly fed into the reaction system, 
meanwhile produced polymer particles are taken out. 
As the method for stopping the reaction without adding any deactivator, 
conventional methods can be employed. For example, 
(1) The feeding of a solid catalyst component and organoaluminum compound 
into a reactor is stopped, the feed of gases including olefin is reduced 
in proportion to the lowering of rate of reaction, and after the rate of 
reaction is lowered to a certain level, e.g. a half or a third of regular 
value, all the feeding of reactant gases is stopped; or 
(2) The feeding of all gases is stopped simultaneously with the stopping of 
the feeds of solid catalyst component and organoaluminum compound and the 
pressure and temperature are lowered. 
In any method for stopping, the pressure and temperature in the reaction 
system are lowered and gases in the reaction system are purged with an 
inert gas such as nitrogen after the termination of reaction. 
When a reaction is stopped by introducing a deactivator, it is only 
necessary to introduce the deactivator into the reaction system. The 
feeding of olefins, solid catalyst component and organoaluminum compound 
may be either continued or discontinued. The temperature and pressure in 
the reaction system may be maintained as they are or lowered sometimes. 
The deactivators used in the present invention are exemplified by oxygen, 
steam, carbon monoxide, carbon dioxide, alcohols such as methanol and 
ethanol, and ketones such as acetone. These substances may be used in a 
mixture of two or more kinds. As described in the foregoing passage, when 
carbon dioxide gas is used as a deactivator, only the organoaluminum 
compound can be deactivated without substantially deactivating the solid 
catalyst component by previously testing the influence of the deactivator 
on the solid catalyst component so as to avoid the lowering of the 
polymerization activity. 
The above-mentioned deactivator can be introduced into the reaction system 
together with a suitable carrier gas, for example, a reactive gas such as 
an olefin, or preferably a non-reactive gas such as argon or helium, or 
more preferably nitrogen. 
The strict controlling of the feed quantity of the deactivator is 
difficult. It is introduced into the reaction system generally in a large 
excess amount because of the reason that the catalyst must be completely 
deactivated. After confirming the stop of the reaction, excess deactivator 
is discharged out of the system. If necessary, the inner part of the 
reaction system is replaced with an inert gas such as nitrogen. 
According to the present invention, the polymer produced by polymerization 
is held intact in the reactor without being discharged until the operation 
is restarted. There is no limit in time length to retain the polymer as 
far as the airtightness of the reaction vessel is maintained and the time 
of several weeks or longer may be allowable. That is, when a reaction is 
stopped on account of any trouble in the succeeding processes (e.g. powder 
treating step, pelletizing step or blending step) or in a circulation gas 
blower in the reaction system, the polymer can be maintained in a reactor 
until the necessary repair work is completed. 
In the case that a deactivator is supplied, when the quantity of remaining 
deactivator is small in a reactor, the operation can be restarted by 
feeding a large quantity of an organoaluminum compound to the reaction 
system. However, the reaction system is usually supplied with a large 
quantity of deactivator to stop the reaction, a considerable quantity of 
deactivator remains in the reaction system before the restarting. 
Accordingly, the remaining deactivator is preferably discharged as 
completely as possible before the restarting of operation. For this 
reason, the purging of reaction system is done using an inert gas to 
displace the gaseous deactivator with the inert gas. Nitrogen is 
preferable as the inert gas. The above gas displacement can be done just 
after the stopping of reaction. 
The displacement may be done by continuously passing nitrogen through a 
reaction system or by pressurizing the reaction system with nitrogen and 
discharging it through a vent port. 
The concentration of gaseous deactivator remaining in the reaction system 
after the venting is generally less than 10 ppm, preferably less than 1 
ppm, and more preferably less than 0.1 ppm. In the case of carbon dioxide, 
however, the concentration thereof is less than 50 ppm and preferably less 
than 5 ppm. 
According to the present invention, the polymer particles are retained in 
the reaction system until the restarting of operation, at the same time, 
the operation is restarted with firstly feeding an organoaluminum 
compound. In other words, the organoaluminum compound is supplied before 
the feeding of solid catalyst component. It may be considered that only a 
solid catalyst component is fed in the first place or both the solid 
catalyst component and an organoaluminum compound are fed simultaneously. 
However, in the present invention, it is important that only the 
organoaluminum compound is fed in the first place. 
It is desirable that the feeding of organoaluminum compound before the 
restarting of operation is carried out with circulating nitrogen in the 
reaction system in order to make the dispersion of organoaluminum compound 
uniform. 
Incidentally, the pressure to circulate nitrogen is in the range of 0 to 10 
kgf/cm.sup.2 .multidot.G, preferably 3 to 6 kgf/cm.sup.2 .multidot.G. The 
temperature is the same as the polymerization temperature of generally 
10.degree. to 200.degree. C., preferably 40.degree. to 150.degree. C. 
The quantity of organoaluminum compound to be fed in the restarting of 
operation may be the same as the feed rate in regular operation, however, 
it is preferably determined in view of the factors whether the deactivator 
was used or not and the quantity of organoaluminum compound remained in 
the reaction system before the stop of reaction. 
When the deactivator is not used, the quantity of organoaluminum compound 
to be fed is such an amount corresponding to 0.2 to 10 aluminum atoms, 
preferably 0.5 to 5 atoms and more preferably 1 to 2 aluminum atoms per 1 
aluminum atom in the organoaluminum compound remaining in the reaction 
system. Even when a corresponding amount up to more than 10 aluminum atoms 
is used, any additional effect is not produced which is uneconomical. 
When a gaseous deactivator is used, the quantity of organoaluminum compound 
to be fed is such an amount corresponding to 1 or more aluminum atoms, 
preferably more than 2 aluminum atoms per 1 aluminum atom in the remaining 
organoaluminum compound. Even if it is fed to a large excess, the effect 
thereof is not so increased and it is uneconomical, so that the maximum 
quantity of the organoaluminum compound to be fed is an amount 
corresponding to 100 aluminum atoms per 1 aluminum atom in the 
organoaluminum compound remaining in the reaction system. Especially, when 
carbon dioxide is used as a gaseous deactivator, an amount corresponding 
to 2 or more aluminum atoms, more preferably more than 3 aluminum atoms of 
organoaluminum compound may be fed per 1 aluminum atom of the remaining 
organoaluminum compound. 
The term "reaction system" includes the spaces among polyolefin particles 
in a reactor, in circulated gases, and the parts inside walls of several 
apparatus in the reaction system. The rate of feed can be optionally 
selected. The quantity of organoaluminum compound remaining in the 
reaction system before the stopping can be determined as a product of the 
feed rate of organoaluminum compound multiplied by an average residence 
time in the reactor for polymer particles. 
After feeding a predetermined quantity of organoaluminum compound, olefin 
gases and hydrogen as a molecular weight modifier are fed with the 
circulation of nitrogen, thereby gradually raising the pressure by these 
materials. It is preferable that the ratios of the feeds of olefin gases 
and hydrogen are made equal respectively to the ratios of the final 
composition in the reaction system. 
The solid catalyst component is then supplied into the reaction system 
together with an inert gas such as nitrogen. The polymerization is started 
simultaneously with the feeding of the solid catalyst component and the 
quantity of produced polyolefin is gradually increased to attain the 
conditions of regular operation. 
After that, the polymerization can be made to proceed under regular 
conditions by feeding predetermined quantities of olefins, solid catalyst 
component and organoaluminum compound. 
The function of carbon dioxide as a deactivator is described in the 
following. 
Although the strict mechanism to stop the reaction with carbon dioxide is 
not clear, it is considered that carbon dioxide gas reacts with an 
organoaluminum compound to consume it and, as a result, the polymerization 
is stopped. In the following description, one of the alkylaluminums, 
triethyl aluminum (AlEt.sub.3) was used as an organoaluminum compound. 
AlEt.sub.3 is extinguished at a temperature below 100.degree. C. through 
the following reaction formula: 
EQU CO.sub.2 +AlEt.sub.3 .fwdarw.Et.sub.2 AlO.multidot.CO.multidot.Et 
As a result, Et.sub.2 AlO.multidot.CO.multidot.Et in an equimolar amount 
with AlEt.sub.3 in the reaction system is formed and the latter compound 
remains in the reaction system. 
When the operation is restarted, in order to avoid that the newly added 
AlEt.sub.3 is consumed by the carbon dioxide through the above reaction, 
the carbon dioxide gas remaining in the reaction system is purged with an 
inert gas. 
AlEt.sub.3 is then newly fed. The newly introduced AlEt.sub.3 is firstly 
consumed by the above reaction product of Et.sub.2 
AlO.multidot.CO.multidot.Et through the following formula: 
EQU Et.sub.2 AlO.multidot.CO.multidot.Et+AlEt.sub.3 .fwdarw.[Et.sub.2 
AlO].sub.2 CEt.sub.2 
EQU [Et.sub.2 AlO].sub.2 CEt.sub.2 +AlEt.sub.3 .fwdarw.Et.sub.2 AlOCEt.sub.3 
+[Et.sub.2 Al].sub.2 O 
The quantity of newly fed AlEt.sub.3 which is consumed by the reaction with 
the Et.sub.2 AlO.multidot.CO.multidot.Et is 2 times by mole of the 
Et.sub.2 AlO.multidot.CO.multidot.Et remained in the reaction system. The 
above final products of Et.sub.2 AlOCEt.sub.3 and [Et.sub.2 Al].sub.2 O 
are stable and inert to the polymerization reaction. 
Accordingly, the newly fed AlEt.sub.3 can produce the effect as a 
co-catalyst when it is fed more than twice by mole of the above Et.sub.2 
AlO.multidot.CO.multidot.Et, that is, more than twice the moles of 
AlEt.sub.3 which remained in the reaction system when the reaction was 
stopped. Furthermore, when 3 times by moles as much as the above quantity 
is fed, the resultant quantity corresponds to the quantity of AlEt.sub.3 
just before the urgent stop of the reaction. Therefore, it is desirable to 
feed more than 3 times by mole of AlEt.sub.3 in the restarting operation. 
In the above description, a trialkyl aluminum of AlEt.sub.3 was exemplified 
as an organoaluminum compound. Any organoaluminum compound having a 
carbon-aluminum bond has the same function as the above. Accordingly, when 
carbon dioxide gas is used as a deactivator, any one of organoaluminum 
compound to be fed is preferably in the quantity corresponding to 2 or 
more aluminum atoms relative to 1 aluminum atom remained in the reaction 
system at the stopping of reaction. 
In the following, the present invention will be described in more detail 
with reference to examples and comparative examples. It should be noted, 
however, that the present invention is by no means restricted to these 
examples and comparative examples. 
EXAMPLE 
Preparation Example for Solid Catalyst Components 
A 500 ml three-necked flask equipped with a stirrer and a reflux condenser 
was fed with 50 g of SiO.sub.2 which was baked at 600.degree. C., 160 ml 
of dehydrated hexane and 2.2 ml of titanium tetrachloride. The contents 
were allowed to react for 3 hours under the refluxing with hexane. After 
the reaction, the reaction mixture was cooled and 30 ml of diethylaluminum 
chloride solution in hexane (1 mmol/ml) was added. Reaction was further 
carried out for 2 hours under the refluxing with hexane and the reaction 
mixture was dried under reduced pressure at 120.degree. C. to remove the 
hexane. The thus obtained reaction product is hereinafter referred to as 
"Component I". 
A stainless steel pot of 400 ml in internal volume containing 25 of 
stainless steel balls of 0.5 inch in diameter, was fed with 10 g of 
commercially available anhydrous magnesium chloride and 4.2 g of aluminum 
triethoxide. Ball milling was carried out at room temperature for 16 hours 
in an atmosphere of nitrogen. The thus obtained reaction product is 
hereinafter referred to as "Component II". 
The above Component II (5.4 g) was dissolved into 160 ml of dehydrated 
ethanol and the whole solution was fed into a three-necked flask 
containing Component I. Reaction was carried out for 3 hours under the 
refluxing of ethanol. After that, drying under reduced pressure was then 
carried out at 150.degree. C. for 6 hours to obtain a solid catalyst 
component. The content of titanium was 15 mg per 1 g of the obtained solid 
catalyst component. 
The reaction for the preparation of the solid catalyst component was 
performed in an inert gas atmosphere to avoid the contamination with 
moisture. 
EXAMPLE 1 
A fluidized bed reactor 1 of 25 cm in diameter as shown in FIG. 1 was used. 
Seed polymer of 12 kg of linear low density polyethylene having an average 
diameter of 810 .mu.m was previously dried and it was fed to the reactor. 
The pressure in the reaction system was raised to 5 kgf/cm.sup.2 
.multidot.G with nitrogen gas. By using a blower 13, the gas in the 
reaction system was circulated at a flow rate of 88 m.sup.3 /hr through 
the fluidized bed reactor 1, a gas circulation piping 12, the blower 13 
and a cooler 14. The temperature in the system was maintained at 
85.degree. C. by regulating the temperature of the circulated gas. The 
feed rates of gases were so adjusted that the molar ratio of 
hydrogen/ethylene/butene-1 was 0.1/1/0.4, the concentration of nitrogen 
was 25 mol. % and the total pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from a co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from a catalyst feed pipe 8 at a rate of 1.0 g/hr, thereby 
starting the polymerization reaction. The reaction reached steady state 
after 12 hours and the operation was smoothly continued after that. 
The rate of formation of ethylene-butene-1 copolymer obtained through 
polymer particle outlet valves 15 and 16 was 4.0 kg/hr. The properties of 
the product were 0.90 g/10 min. in MFR, 0.921 g/cm.sup.3 in density, 780 
.mu.m in average particle diameter with clear and white appearance and 
spherical shape. 
The quantity of polymer particles remaining in the fluidized bed reactor 
was estimated to be 12 kg with the indication of a differential pressure 
gauge (not shown in the drawing). Accordingly, the average residence time 
of polymer particles was 3 hours. 
In the next step, the feeds of solid catalyst component and 
triethylaluminum were stopped to cease the polymerization reaction. Just 
after that, the temperature of the circulation gas at the inlet of the 
polymerization reactor was raised. At the time when the difference between 
the inlet gas temperature and the reaction temperature was reduced to one 
third of the steady state period, the feed of olefins were stopped. 
The circulation gas was discharged from a vent pipe 11 to lower the 
pressure in the system to 6 kgf/cm.sup.2 .multidot.G over 20 minutes. At 
the same time, the temperature was lowered to 50.degree. C. The gases in 
the system were discharged with the blower 13 at a rate of 16 m.sup.3 /hr 
from the vent pipe. Meanwhile, nitrogen was introduced from a nitrogen 
feed pipe 10 to maintain the pressure at 6 kgf/cm.sup.2 .multidot.G. 
The blower 13 was stopped after 5 hours and gases were discharged from the 
vent pipe 11 until the pressure in the system was lowered to the 
atmospheric pressure. The pressure in the system was then raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen and released the pressure to the 
atmospheric pressure. This operation was repeated three times to purge the 
olefin gases. 
The polymer particles were retained in the fluidized bed reactor for 48 
hours. 
The pressure in the fluidized bed reactor was raised to 5 kgf/cm.sup.2 
.multidot.G with nitrogen and the gas in the reaction system was 
circulated at a flow rate of 88 m.sup.3 /hr by using the blower 13. The 
temperature in the system was raised to 85.degree. C. by adjusting the 
temperature. After that, triethylaluminum was fed at a rate of 3.3 g/hr 
for 1 hour (total: 3.3 g). This quantity was almost the same as the 
triethylaluminum remaining in the reaction system before the stopping of 
reaction. 
In the next succeeding step, gases were fed in the molar ratio of 
hydrogen/ethylene/butene-1 of 0.1/1/0.4 and the concentration of nitrogen 
was made 25 mol. % and the total pressure was raised to 20 kgf/cm.sup.2 
.multidot.G. 
After the total pressure reached 20 kgf/cm.sup.2 .multidot.G, 1.1 g/hr of 
triethylaluminum and 1.0 g/hr of the solid catalyst component were fed 
respectively in the like manner as the start of operation. The reaction 
became steady state after 6 hours and the rate of formation of polymer 
particles was 4.0 kg/hr like the start of operation. The operation could 
be continued smoothly. 
The ethylene-butene-1 copolymer was 0.89 g/10 min. in MFR and 0.921 
g/cm.sup.3 in density. These values were consistent with those of the 
polymer particles obtained in the initial operation. 
Incidentally, all the Examples and Comparative Examples disclosed herein 
were carried out independently. The respective experiments were done with 
the intervals of several days to several weeks. More particularly, the 
polymerization apparatus after each experiment was exposed to the air for 
gas purging according to predetermined procedures. The start of experiment 
was done likewise. The methods for preparing catalysts were the same. 
However, prior to each experiment, only a certain amount of catalyst 
necessary for the experiment was prepared and it was use for only the 
relevant experiment. 
COMATIVE EXAMPLE 1 
Experiment was carried out in the like manner as in Example 1 except that 
the feeding of triethylaluminum (3.3 g/hr for 1 hour, 3.3 g in total) 
before the restarting of operation was not done. That is, the operation 
was started again by feeding olefins in the same rate as the regular 
operation and 1.0 g/hr of the solid catalyst component and 1.1 g/hr of 
triethylaluminum into the reactor. 
As a result, the reaction was hardly started and, 12 hours later on, the 
polymerization was started. In addition, sheet-like polymer was produced 
after the start of reaction and at 15 hours from the feeding of the solid 
catalyst component, the operation was stopped because the zone from the 
fluidized bed reactor to the polymer outlet pipe was blocked. 
COMATIVE EXAMPLE 2 
In Example 1, triethylaluminum was fed at a rate of 3.3 g/hr for 1 hour 
(3.3 g in total) and the operation was subsequently started. In this 
Comparative Example, however, the feeding of triethylaluminum was done 
simultaneously with the feeding of the solid catalyst component. Other 
operation conditions were the same as those in Example 1. 
In other words, in the restarting of operation, olefins, solid catalyst 
component and triethylaluminum were simultaneously fed and the ratio and 
rate of feeding of olefins and 1.0 g/hr of solid catalyst component were 
the same as those in the steady state operation. The feeding of 
triethylaluminum was done at a rate of 3.3 g/hr which was the same as the 
value in restarting operation in Example 1. 
The polymerization was started 30 minutes after the start of feeding of 
reactant materials, however, chip-like polymer was formed. After 1 hour, 
the feed rate of triethylaluminum was changed from 3.3 g/hr to 1.1 /hr 
which was the feed rate in the regular state in Example 1. After 1 hour 
and 45 minutes, the operation was stopped because the blocking was caused 
to occur in the zone from the fluidized bed reactor to the polymer outlet 
pipe. 
COMATIVE EXAMPLE 3 
The operation was started in the like manner as in Example 1 and after that 
the polymerization was stopped. All the polymer particles in the fluidized 
bed reactor were then discharged from the reaction system. 
After that, in order to restart the operation, 12 kg of previously dried 
seed polymer of linear low density polyethylene of 810 .mu.m in average 
particle diameter was newly fed into the fluidized bed reactor. The inside 
of the system was purged with nitrogen and operation was done in the like 
manner as in the start of the initial operation in Example 1. That is, the 
pressure in the reaction system was raised to 5 kgf/cm.sup.2 .multidot.G 
with nitrogen gas. By using a blower 13, the gas in the reaction system 
was circulated at a flow rate of 88 m.sup.3 /hr through the fluidized bed 
reactor 1, gas circulation piping 12, blower 13 and cooler 14. The 
temperature in the system was maintained at 85.degree. C. by regulating 
the temperature of the circulated gas. The feed rates of gases were so 
adjusted that the molar ratio of hydrogen/ethylene/butene-1 was 0.1/1/0.4, 
the concentration of nitrogen was 25 mol. % and the total pressure was 20 
kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from a co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from a catalyst feed pipe 8 at a rate of 1.0 g/hr, thereby 
starting the polymerization reaction. 
However, the polymerization was hardly started because of the existence of 
impurities in the system and it took 4 days to return the operation to 
regular condition. 
EXAMPLE 2 
The fluidized bed reactor 1 of 25 cm in diameter shown in FIG. 1 was used 
in the like manner as in Example 1. 
In operation, 12 kg of previously dried linear low density polyethylene of 
780 .mu.m in average particle diameter as seed polymer was fed into the 
fluidized bed reactor. The pressure in the reaction system was raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen gas. By using the blower 13, the 
gas in the reaction system was circulated at a flow rate of 88 m.sup.3 /hr 
through the fluidized bed reactor 1, gas circulation piping 12, blower 13 
and cooler 14. The temperature in the system was maintained at 85.degree. 
C. by regulating the temperature of the circulated gas. The feed rates of 
gases were so adjusted that the molar ratio of hydrogen/ethylene/butene-1 
was 0.1/1/0.4, the concentration of nitrogen was 25 mol. % and the total 
pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from a co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from a catalyst feed pipe 8 at a rate of 0.8 g/hr, thereby 
starting polymerization reaction. Regular operation of reaction was 
attained after 15 hours and the operation could be continued smoothly 
after that. 
The ethylene-butene-1 copolymer was taken out through polymer particle 
outlet valves 15 and 16 at a rate of 4.0 kg/hr. It was clear white 
particles of 0.88 g/10 min. in MFR, 0.9208 g/cm.sup.3 in density and 760 
.mu.m in average particle diameter. 
Incidentally, the quantity of polymer particles remaining in the fluidized 
bed reactor was estimated to be 12 kg with the indication of a 
differential pressure gauge (not shown in the drawing). Accordingly, the 
average residence time of polymer particles was 3 hours. 
In the next step, 3 g of carbon monoxide gas was fed into the circulation 
gas through the gaseous deactivator feed pipe 9 to urgently cease the 
polymerization reaction. Just after that, the temperature of the 
circulation gas at the inlet of polymerization reactor was raised rapidly 
and the rise of differential pressure of the fluidized bed was also 
stopped, thereby confirming the stopping of the polymerization reaction. 
The circulation gas was discharged from a vent pipe 11 to lower the 
pressure in the system to 6 kgf/cm.sup.2 .multidot.G over 20 minutes. At 
the same time, the temperature was lowered to 50.degree. C. The gases in 
the system were discharged through the blower 13 at a rate of 16 m.sup.3 
/hr from the vent pipe. Meanwhile, nitrogen was introduced from a nitrogen 
feed pipe 10 to maintain the pressure at 6 kgf/cm.sup.2 .multidot.G. 
The blower 13 was stopped after 5 hours and gases were discharged from the 
vent pipe 11 until the pressure in the system was lowered to the 
atmospheric pressure. The pressure in the system was then raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen and the pressure was released to 
atmospheric pressure. This operation was repeated three times to purge the 
carbon monoxide gas. 
The polymer particles were retained in the fluidized bed reactor for 20 
hours. 
The pressure in the fluidized bed reactor was raised to 5 kgf/cm.sup.2 
.multidot.G with nitrogen and the gas in the reaction system was 
circulated at a flow rate of 88 m.sup.3 /hr by using the blower 13. The 
temperature in the system was raised to 85.degree. C. by adjusting the 
temperature. The concentration of carbon monoxide in the circulation gas 
at this step was 0.1 ppm. After that, triethylaluminum was fed at a rate 
of 10 g/hr for 2 hours (20 g in total). This quantity corresponded 6.1 
times the quantity of triethylaluminum which remained in the polymer 
particles before the reaction stopping. 
In the succeeding step, gases were fed in the molar ratio of 
hydrogen/ethylene/butene-1 of 0.1/1/0.4 and the concentration of nitrogen 
was made 25 mol. % and the total pressure was raised to 20 kgf/cm.sup.2 
.multidot.G. 
After the total pressure reached 20 kgf/cm.sup.2 .multidot.G, 1.1 g/hr of 
triethylaluminum and 0.8 g/hr of the solid catalyst component were fed 
respectively in the like manner as the start of operation. The reaction 
became steady state after 12 hours and the rate of formation of polymer 
particles was 4.0 kg/hr like the start of operation. The operation could 
be continued smoothly. 
The obtained ethylene-butene-1 copolymer was 0.85 g/10 min. in MFR and 
0.9211 g/cm.sup.3 in density. These values were consistent with those of 
the polymer particles obtained in the initial operation. 
COMATIVE EXAMPLE 4 
Experiment was carried out in the like manner as in Example 2 except that 
the feeding of triethylaluminum (10 g/hr for 2 hours, 20 g in total) 
before the restarting of operation was not done. That is, the operation 
was started again by feeding olefins, solid catalyst component and 
triethylaluminum into the reactor in the same rates as the regular 
operation. 
As a result, the reaction was hardly started and, 14 hours later on, the 
polymerization was started again. In addition, sheet-like polymer was 
produced after that and after 18 hours from the feeding of the solid 
catalyst component, the operation was stopped because the zone from the 
fluidized bed reactor to the polymer outlet pipe was blocked. 
COMATIVE EXAMPLE 5 
In Example 2, after the purge of carbon monoxide with nitrogen, 
triethylaluminum was fed at a rate of 10 g/hr for 2 hours and the 
operation was subsequently started. In this Comparative Example, however, 
the feeding of triethylaluminum was done simultaneously with the feeding 
of the solid catalyst component. Other operation conditions were the same 
as those in Example 2. 
In other words, in the restarting of operation, olefins, solid catalyst 
component and triethylaluminum were simultaneously fed. The feeding of 
triethylaluminum was done at a rate of 10 g/hr which is the same as in the 
restarting operation in Example 2. 
The polymerization was started 1 hour and 15 minutes after the start of 
feeding of reactant materials, however, chip-like polymer was formed. 
After 2 hours, the feed rate of triethylaluminum was changed from 10 g/hr 
to 1.1 g/hr which was the same as the feed rate in the regular state in 
Example 2. After 2 hours and 45 minutes, the operation was stopped because 
the blocking was caused to occur in the zone from the fluidized bed 
reactor to the polymer outlet pipe. 
COMATIVE EXAMPLE 6 
The operation was started in the like manner as in Example 2 and after that 
the polymerization was stopped by feeding carbon monoxide gas. All the 
polymer particles in the fluidized bed reactor were then discharged from 
the reaction system. 
After that, in order to restart the operation, 12 kg of previously dried 
seed polymer of linear low density polyethylene of 780 .mu.m in average 
particle diameter was newly fed into the fluidized bed reactor. The inside 
of the system was purged with nitrogen and the restarting of operation was 
done in the like manner as in the start of the initial operation in 
Example 2. That is, the pressure in the reaction system was raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen gas. By using the blower 13, the 
gas in the reaction system was circulated at a flow rate of 88 m.sup.3 /hr 
through the fluidized bed reactor 1, gas circulation piping 12, blower 13 
and cooler 14. The temperature in the system was maintained at 85.degree. 
C. by regulating the temperature of the circulated gas. The feed rates of 
gases were so adjusted that the molar ratio of hydrogen/ethylene/butene-1 
was 0.1/1/0.4, the concentration of nitrogen was 25 mol. % and the total 
pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from a co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from a catalyst feed pipe 8 at a rate of 0.8 g/hr, thereby 
starting the polymerization reaction. 
However, the polymerization was hardly stabilized because of the existence 
of impurities in the system and it took 5 days to return the operation to 
regular condition. 
EXAMPLE 3 
The fluidized bed reactor 1 of 25 cm in diameter shown in FIG. 1 was used. 
In operation, 12 kg of previously dried linear low density polyethylene of 
830 .mu.m in average particle diameter as seed polymer was fed into the 
fluidized bed reactor. The pressure in the reaction system was raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen gas. By using the blower 13, the 
gas in the reaction system was circulated at a flow rate of 88 m.sup.3 /hr 
through the fluidized bed reactor 1, gas circulation piping 12, blower 13 
and cooler 14. The temperature in the system was maintained at 85.degree. 
C. by regulating the temperature of the circulated gas. The feed rates of 
gases were so adjusted that the molar ratio of hydrogen/ethylene/butene-1 
was 0.1/1/0.4, the concentration of nitrogen was 25 mol. % and the total 
pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 0.5 g/hr of triethylaluminum in the form of a hexane 
solution was fed from the co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from the catalyst feed pipe 8 at a rate of 0.8 g/hr, 
thereby starting polymerization reaction. Regular operation of reaction 
was attained after 12 hours and the operation could be continued smoothly 
after that. 
The ethylene-butene-1 copolymer was taken out through polymer particle 
outlet valves 15 and 16 at a rate of 3.8 kg/hr. It was clear white 
particles of 1.0 g/10 min. in MFR, 0.9185 g/cm.sup.3 in density and 810 
.mu.m in average particle diameter. 
Incidentally, the quantity of polymer particles remained in the fluidized 
bed reactor was estimated to be 12 kg according to the indication of a 
differential pressure gauge (not shown in the drawing). Accordingly, the 
average residence time of polymer particles was 3.2 hours. 
In the next step, 1 lit. of dried air of 20.degree. C. at atmospheric 
pressure (8.3 mmol as oxygen) was pressurized with nitrogen and was fed 
into the circulation gas through the gaseous deactivator feed pipe 9 to 
urgently cease the polymerization reaction. Just after that, the 
temperature of the circulation gas for cooling was raised rapidly and the 
rise of differential pressure of the fluidized bed was also stopped, 
thereby confirming the stopping of the polymerization reaction. 
The circulation gas was discharged from the vent pipe 11 to lower the 
pressure in the system to 5 kgf/cm.sup.2 .multidot.G over 20 minutes. At 
the same time, the temperature was lowered to 50.degree. C. The gases in 
the system were discharged through the blower 13 at a rate of 16 m.sup.3 
/hr from the vent pipe. Meanwhile, nitrogen was introduced from the 
nitrogen feed pipe 10 to maintain the pressure at 5 kgf/cm.sup.2 
.multidot.G. 
The blower 13 was stopped after 4 hours and gases were discharged from the 
vent pipe 11 until the pressure in the system was lowered to the 
atmospheric pressure. The pressure in the system was then raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen and released the pressure to the 
atmospheric pressure. This operation was repeated three times to purge the 
oxygen. 
The polymer particles were retained in the fluidized bed reactor for 65 
hours. 
The pressure in the fluidized bed reactor was raised to 5 kgf/cm.sup.2 
.multidot.G with nitrogen and the gas in the reaction system was 
circulated at a flow rate of 88 m.sup.3 /hr by using the blower 13. The 
temperature in the system was raised to 85.degree. C. by adjusting the 
temperature. The concentration of oxygen in the circulation gas at this 
step was 1 ppm. After that, triethylaluminum was fed at a rate of 5 g/hr 
for 2 hours (10 g in total). This quantity corresponded 6.3 times the 
quantity of triethylaluminum which remained in the polymer particles 
before the stopping of reaction. 
In the succeeding step, gases were fed in the molar ratio of 
hydrogen/ethylene/butene-1 of 0.1/1/0.4 and the concentration of nitrogen 
was made 25 mol. % and the total pressure was raised to 20 kgf/cm.sup.2 
.multidot.G. 
After the total pressure reached 20 kgf/cm.sup.2 .multidot.G, 0.5 g/hr of 
triethylaluminum and 0.8 g/hr of solid catalyst component were fed 
respectively in the like manner as the initial start of operation. The 
reaction reached steady state after 16 hours and the rate of formation of 
polymer particles was 3.8 kg/hr which is similar to the start of 
operation. The operation could be continued smoothly. 
The obtained ethylene-butene-1 copolymer was 0.95 g/10 min. in MFR and 
0.9190 g/cm.sup.3 in density. These values were consistent with those of 
the polymer particles obtained in the initial operation. 
EXAMPLE 4 
The fluidized bed reactor 1 of 25 cm in diameter shown in FIG. 1 was used. 
In operation, 12 kg of previously dried linear low density polyethylene of 
810 .mu.m in average particle diameter as seed polymer was fed into the 
fluidized bed reactor. The pressure in the reaction system was then raised 
to 5 kgf/cm.sup.2 .multidot.G with nitrogen gas. By using the blower 13, 
the gas in the reaction system was circulated at a flow rate of 88 m.sup.3 
/hr through the fluidized bed reactor 1, gas circulation piping 12, blower 
13 and cooler 14. The temperature in the system was maintained at 
85.degree. C. by regulating the temperature of the circulated gas. The 
feed rates of gases were so adjusted that the molar ratio of 
hydrogen/ethylene/butene-1 was 0.1/1/0.4, the concentration of nitrogen 
was 25 mol. % and the total pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from the co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from the catalyst feed pipe 8 at a rate of 1.0 g/hr, 
thereby starting the polymerization reaction. Regular operation of 
reaction was attained after 12 hours and the operation could be continued 
smoothly after that. 
The ethylene-butene-1 copolymer was taken out through polymer particle 
outlet valves 15 and 16 at a rate of 4.0 kg/hr. It was clear white 
particles of 0.90 g/10 min. in MFR, 0.9210 g/cm.sup.3 in density and 780 
.mu.m in average particle diameter. 
Incidentally, the quantity of polymer particles remained in the fluidized 
bed reactor was estimated to be 12 kg according to the indication of a 
differential pressure gauge (not shown in the drawing). Accordingly, the 
average residence time of polymer particles was 3 hours. 
In the next step, 17 g of carbon dioxide gas was fed into the circulation 
gas through the carbon dioxide feed pipe 9 to urgently cease the 
polymerization reaction. Just after that, the temperature of the 
circulation gas for cooling was raised rapidly and the rise of 
differential pressure of the fluidized bed was also stopped, thereby 
confirming the stopping of the polymerization reaction. 
The circulation gas was discharged from the vent pipe 11 to lower the 
pressure in the system to 6 kgf/cm.sup.2 .multidot.G over 20 minutes. At 
the same time, the temperature was lowered to 50.degree. C. The gases in 
the system were discharged through the blower 13 at a rate of 16 m.sup.3 
/hr from the vent pipe. Meanwhile, nitrogen was introduced from the 
nitrogen feed pipe 10 to maintain the pressure at 6 kgf/cm.sup.2 
.multidot.G. 
The blower 13 was stopped after 5 hours and gases were discharged from the 
vent pipe 11 until the pressure in the system was lowered to the 
atmospheric pressure. The pressure in the system was then raised to 5 
kgf/cm.sup.2 .multidot.G with nitrogen and released the pressure to the 
atmospheric pressure. This operation was repeated three times to purge the 
carbon dioxide. 
The polymer particles were retained in the fluidized bed reactor for 40 
hours. 
The pressure in the fluidized bed reactor was raised to 5 kgf/cm.sup.2 
.multidot.G with nitrogen and the gas in the reaction system was 
circulated at a flow rate of 88 m.sup.3 /hr by using the blower 13. The 
temperature in the system was raised to 85.degree. C. by adjusting the 
temperature. The concentration of carbon dioxide in the circulation gas at 
this step was 4 ppm. After that, triethylaluminum was fed at a rate of 5 
g/hr for 2 hours (10 g in total). This quantity corresponded to about 3 
times the quantity of triethylaluminum which remained in the polymer 
particles before the stopping of reaction. 
In the succeeding step, gases were fed in the molar ratio of 
hydrogen/ethylene/butene-1 of 0.1/1/0.4 and the concentration of nitrogen 
was made 25 mol. % and the total pressure was raised to 20 kgf/cm.sup.2 
.multidot.G. 
After the total pressure reached 20 kgf/cm.sup.2 .multidot.G, 1.1 g/hr of 
triethylaluminum and 1.0 g/hr of solid catalyst component were fed 
respectively in the like manner as the initial start of operation. The 
reaction reached steady state after 6 hours and the rate of formation of 
polymer particles was 4.0 kg/hr which is similar to the start of 
operation. The operation could be continued smoothly. 
The obtained ethylene-butene-1 copolymer was 0.91 g/10 min. in MFR and 
0.9208 g/cm.sup.3 in density. These values were consistent with those of 
the polymer particles obtained in the initial operation. 
COMATIVE EXAMPLE 7 
Experiment was carried out in the like manner as in Example 4 except that 
the feeding of triethylaluminum (5 g/hr for 2 hours, 10 g in total) before 
the restarting of operation was not done. That is, the operation was 
started again by feeding olefins, solid catalyst component and 
triethylaluminum in the same rate as the regular operation into the 
reactor. 
As a result, the reaction was hardly started and, 12 hours later on, the 
polymerization was started. In addition, sheet-like polymer was produced 
after the start of reaction and at 15 hours from the feeding of the solid 
catalyst, the operation was stopped because the zone from the fluidized 
bed reactor to the polymer outlet pipe was blocked. 
COMATIVE EXAMPLE 8 
In Example 4, 5 g/hr of triethylaluminum was fed for 2 hours (10 g in 
total) after the purging with carbon dioxide gas and the operation was 
subsequently started. In this Comparative Example, however, the feeding of 
triethylaluminum was done simultaneously with the feeding of the solid 
catalyst component. Other operation conditions were the same as those in 
Example 4. 
In other words, in the restarting of operation, olefins, solid catalyst 
component and triethylaluminum were simultaneously fed and the rate of 
feeding of olefins and solid catalyst component were the same as those in 
regular state operation. The feeding of triethylaluminum was done at a 
rate of 5 g/hr which was the same as the value in the restarting operation 
in Example 4. 
The polymerization was started at 1 hour and 15 minutes after the start of 
feeding of reactant materials, however, chip-like polymer was formed. 
After 2 hours, the feed rate of triethylaluminum was changed from 5 g/hr 
to 1.1/hr which was the feed rate in the steady state in Example 4. After 
2 hours and 45 minutes, the operation was stopped because the blocking was 
caused to occur in the zone from the fluidized bed reactor to the polymer 
outlet pipe. 
COMATIVE EXAMPLE 9 
The operation was started in the like manner as in Example 4 and the 
polymerization was stopped by the feed of carbon dioxide gas. All the 
polymer particles in the fluidized bed reactor were then taken out of the 
reaction system. 
After that, in order to restart the operation, 12 kg of previously dried 
seed polymer of linear low density polyethylene of 810 .mu.m in average 
particle diameter was newly fed into the fluidized bed reactor. The inside 
of the system was purged with nitrogen and operation was done in the like 
manner as in the start of the initial operation in Example 4. That is, the 
pressure in the reaction system was raised to 5 kgf/cm.sup.2 .multidot.G 
with nitrogen gas. By using a blower 13, the gas in the reaction system 
was circulated at a flow rate of 88 m.sup.3 /hr through the fluidized bed 
reactor 1, gas circulation piping 12, blower 13 and cooler 14. The 
temperature in the system was maintained at 85.degree. C. by regulating 
the temperature of the circulated gas. The feed rates of gases were 
adjusted such that the molar ratio of hydrogen/ethylene/butene-1 was 
0.1/1/0.4, the concentration of nitrogen was 25 mol. % and the total 
pressure was 20 kgf/cm.sup.2 .multidot.G. 
As a co-catalyst, 1.1 g/hr of triethylaluminum in the form of a hexane 
solution was fed from a co-catalyst feed pipe 5, and the solid catalyst 
component containing Ti and Mg obtained in the foregoing Preparation 
Example was fed from a catalyst feed pipe 8 at a rate of 1.0 g/hr, thereby 
starting polymerization reaction. 
However, the polymerization was hardly started because of the existence of 
impurities in the system and it took 4 days to return the operation to 
regular condition. 
In view of the above experiments, after causing the vapor phase 
polymerization of olefins to stop with or without the use of a deactivator 
and without discharging the polymer particles from the reactor, it is 
possible to restart and continue the reaction within a short-period of 
time without any troubles such as blocking with polymer particles, only by 
feeding a predetermined quantity of organoaluminum compound prior to the 
feeding of a solid catalyst component.