CA1127799A

CA1127799A - Process for preparing a copolymer

Info

Publication number: CA1127799A
Application number: CA337,329A
Authority: CA
Inventors: Mitsuo Matsuno; Kazuo Matsuura; Takeichi Shiraishi; Mituji Miyoshi; Nobuyuki Kuroda
Original assignee: Nippon Oil Corp
Current assignee: Eneos Corp
Priority date: 1978-10-11
Filing date: 1979-10-10
Publication date: 1982-07-13
Also published as: GB2033910A; IT7926370A0; FR2438664A1; JPS5552309A; FR2438664B1; JPS649328B2; IT1125473B; DE2941143A1; GB2033910B

Abstract

ABSTRACT OF THE DISCLOSURE
A process is provided herein for preparing an ethylene-butene-1 copolymer having a melt index ranging from 0 01 to 10 and a density ranging from 0 910 to 0 945 In such process, ethylene and 1 to 30 molt thereof of butene-1 are copolymerized in a substantially solvent-free vapor phase condition and in the presence of a catalyst consisting of a solid substance (namely, one containing a magnesium-containing inorganic solid compound and a titanium compound and/or a vanadium compound) and an organoaluminum compound. The process of this invention provides very easily a medium or low density ethylene polymer which has excellent trans-parency and melts higher and is stronger than conventional low density polyethylenes prepared according to high pressure process. The copoly-mer obtained is superior in transparency and elasticity. It also exhi-bits a very high resistance to impact and to environmental stress crack-ing. Consequently, the copolymer can be formed into films, sheets, hol-low container, electric wires and various other products by means of known methods, e g , extrusion molding, blow molding, injection molding, press forming and vacuum forming, and thus can be used in various appli-cations. Particularly in the field of films, the copolymer is useful be-cause of excellent transparency, anti-blocking property, heat sealing property and flexibility. It is possible to attain an equal or even superior transparency to that of a high pressure process film, and the strength which is a specially important physical property required of a film is much higher than that of a high pressure process polyethylene Besides, a large elongation permits forming of an extremely thin film The crystallinity to relatively high and the heat resistance is good, attordlng an unsticky film of high transparency, for which reason the copolymer is especially suitable for use as a film for packing or agri-cultural use. It is also suited to blow molding because of high trans-parency, stiffness and resistance to environmental stress cracking.

Description

llZ7799 This invention relates to a new process for preparing a medium or low density ethylene copolymer by a vapor phase polymerization using a Ziegler catalyst of high activity.
Polyethylenes prepared by polymerization using a catalyst consis-ting of a transition metal compound and an organometallic compound are gen-erally prepared by the slurry polymerization process. The polyethylenes usually produced are only those having a density not lower than 0.945. Such value is considered to be the limit in order to prevent polymer deposition or fouling on the inner walls or on the stirrer in the interior of the reactor at the time of polymerization.
Medium or low density polyethylenes having a density below 0.945 g/cm are usually prepared by the so-called high pressure process using a radical catalyst. Quite recently, however, a high-temperature solution polymerization process using a Ziegler catalyst has also been tried.
Low density polyethylenes prepared by the high pressure process are advantageous in that they are superior in transparency and flexibility to high density polyethylenes; at the same time, however, they are disad-vantageous in that the melting point is low and films formed therefrom are low in stiffness.

Also, polyethylenes prepared by the high-temperature solution poly-merization process have a poor transparency and films formed therefrom give a sticky impression.
Regarding the production method, the high pressure process requires a very high pressure, thus causing the investment in production facilities to become increased, and also required high power consumption and other operation costs. The high-temperature solution polymerization process is also disadvantageous in that the resulting polyethylene must be handled as solution, thus requiring operation at a relatively low concentration, and resulting in the productivity becoming inferior and the ~ ~ .

~127799 production of polyethylenes of a high grade in molecular weight becoming virtually impossible. Furthermore, the polymers prepared according to the high-temperature solution polymerization process contain a large amount of wax because of a high temperature polymerization, so it is necessary to pro-vide means for the separation thereof. In the solution polymerization at a high temperature, moreover, there briskly occur side reactions s~ch as the hydrogenation and dimerization of ethylene, thus requiring an increased unit of ethylene and that of hydrogen.

In the production of polyolefins, copolymerizing ethylene with other monomers has heretofore been known as a method for lowering the density of polyethylene. However, if a medium or low density polyethylene is pre-pared by the copolymerization of ethylene and ànother comonomer according to a known method, the other comonomer is usually required in an unduly high excess amount, and this fact itself is very disadvantageous when viewed from the standpoint of process. The copolymerization according to the slurry polymerization process involves additional disadvantages in that the by-production of a low grade polymer or a solvent-soluble polymer becomes noticeable and the polymerization product takes in~solvent and becomes milky or mushy. This not only makes the reactor operation and slurry transport difficult, but also results in the separation of solvent from the polymer no longer being easy. Furthermore, adhesion of copolymer to the inside of the reactor occurs due to its fouling and the resulting deterioration in heat transfer characteristics causes the polymerization temperature to become uncontrollable.
In recent years it has been found that, if a transition metal is attached to a magnesium-containing solid carrier, e.g., MgO, Mg(OH)2, MgC12, MgC12, MgCO3 and Mg(OH)Cl, and then combined with an organometallic compound, the rlsulting catalyst system can serve as a catalyst of extremely high ac-tivity in olefin polymerization. It is also known that the reaction product of an organomagnesium compound, e.g. RMgX, R2Mg and RMg(OR),

- 2 -tivity in olefin polymerization. It i5 also known that the reaction product of an organomagnesium compound, e.g. RMgX, R2Mg and RMg(OR), ~ - 2a -llZ7799 and a transition metal compound, can se~ve as a high activity catalyst for olefin polymerization (see, for example, Japanese Patent Publication No.
12105/64, Bengian Patent No. 742,112, Japanese Patent Publication Nos.
13050/68 and 9548/70).
However, even if such high activity catalysts with carrier are used in the slurry polymerization or the high-temperature solution polymeri-zation with a view to preparing medium or low density polyethylenes, the foregoing drawbacks heretofore have not been completely eliminated.
In view of comprehensive studies made concerning the foregoing technical problems, it is an object of a broad aspect of this invention to provide a vapor phase polymerization reaction which can bè carried out in an extremely stable manner and in which the catalyst removing step can be elinimated, so it is possible to provide a vapor phase polymerization pro-cess for ethylene which is very simple as a whole.
It is an object of another aspect of this invention to provide such a process which provides very easily a medium or low density ethylene polymer which has excellent transparency and melts higher and is s~ro~ger,~han conventional low density polyethylenes prepared according to the high pressure process.
Thus, according to one aspect thereof, this invention provides a process for preparing an ethylene-butene-l copolymer having a melt index ranging from 0.01 to 10 and a density ranging from 0.910 to 0.945, which process comprises copolymerizing a mixture of ethylene and 1 to 30 mol%
thereof of butene-l in a substantially solvent-free vapor phase condition in the presence of a catalyst consisting of a solid substance and an or-ganoaluminum compound, the solid substance containing a magnesium-contain-ing inorganic solid compound and at least one of a titanium compound and a vanadium compound.

1~27799 By a variant thereof, the at:least one of a titanium compound and vanadium compound is a halide, alkoxyhalide, oxide or halogenated - 3a -llZ~799 oxide of at least one of titanium and vanadium.
By another variant, the at least one of a titanium compound and vanadium compound is used as the addition product with an organocarboxylic acid ester.
By another variant, the magnesium-containing inorganic solid com-pound is selected from the group consisting of metallic magnesium, ~agnesium hydroxide, magnesium carbonate, magnesium oxide and magnesium chloride.
By still another variant, the magnesium-containing inorganic solid compound is selected from the group consisting of a double salt, a double oxide, a carbonate, a chloride and an hydroxide containing a magnesium atom and a metal selected from the group consisting of silicon, aluminum and calcium.
By yet another variant, the magnesium-containing inorganic solid compound is further treated or reacted with an oxygen-containing compound, a sulfur-containing compound, a hydrocarbon or a halogen-containing substance.
By a further variant, the magnesium-containing inorganic solid compound is contacted with an organocarboxylic acid ester before use.
By another variant, the organoaluminum compound is used as the addition product with an organocarboxylic acid ester.
By yet another variant, the catalyst is prepared in the presence of an organocarboxylic acid ester.
By a variation of these variants, the organocarboxylic acid ester is selected from the group consisting of alkyl-esters of benzoic acid, of anisic acid and of toluic acld.
By another variant, the copolymerization is car~ied out at a tem-perature in the range of from 20 to 110C. and at a pressure in the range of from atmospheric to 70 kg/cm G.
By a further variant, the copolymerization is carried out in the X

~lZ7~799 .

presence of hydrogen.
By a still further variant, before initiating the copolymerization, the catalyst system is contacted with an 0~-olefin having 3 to 12 carbon atoms for 1 minute to 24 hours at a temperature in the range of from 0 to 200C. and at a pressure in the range of from -1 to 100 kg/cm G.
It has now become clear that if a vapor phase polymeriæation reaction is carried out according to the process of aspects of this inven-tion using ethylene and butene-l in a ~uantitative ratio within the range specified herein and also using a catalyst consisting of a solid substance and an organoaluminum compound, in-which the solid substance contains a magnesium-containing inorganic solid compound and at least one of a titanium and a vanadium compound, such polymerization reaction can be performed in extremely high activity and extremely stably with reduced production of coarse or ultra-fine particles and improved particle properties, and also with minimized adhesion to the reactor and conglomeration of polymer par-ticles. It is believed to be quite unexpected and surprising that, accord-ing to the process of aspects of this invention, not only can a vapor phase polymerization reaction be carried out extremely smoothly, but also that medium or low density ethylene copolymers can be obtained easily.
The copolymerization reaction of the process of aspects of this invention can be performed at a relatively low temperature easily to afford medium or low density ethylene copolymers, so that adhesion to the reactor or conglomeration of product is scarecely observed. This point is another advantage of aspects of this invention.
The process of aspects of this invention is also characteristic in that a medium or low density ethylene copolymer having a high melt index can be obtained easily; this point is a further advantage of aspects of this invention. Because of these advantages, the copolymer as set forth herein can be obtained efficiently by vapor phase polymerization.

~lZ77~9 The butene-l polymerized with ethylene in the process of aspects of this invention adjsuts the density and molecular weight of the resulting copolymer, and the copolymer obtained is superior in transparency and elas-ticity. It also exhibits a very high resistance to impact and to environ-mental stress cracking. Consequently, the copolymer prepared according to the process of aspects of this invention can be formed into films, sheets, hollow containers, electric wires and various other products by means of known methods, e.g., extrusion molding, blow molding, injection molding, press forming and vacuum forming, and thus can be used in various applications.
Particularly in the field of films, the copolymer produced according to the process of aspects of this invention is useful because of excellent trans-parency, anti-blocking property, heat sealing property and flexibility. It is thus possible to attain an equal or even superior transparency to that of a high pressure process film, and the strength which is specially important physical property required of a film is much higher than that of a high pressure process polyethylene. Besides, a large elongation permits forming of an extremely thin film.
Athough the density of the copolymer produced according to the pro-cess of aspects of this invention is medium or low, the crystallinity is relatively high and the heat resistance is good, affording an unsticky film of high transparency, for which reason the copolymer produced according to the process of aspects of this invention is especially suitable for use as a film for packing or agricultural use. It is also suited to blow molding be-cause of high transparency, stiffness and resistance to environmental stress cracking.
The catalyst system used in the process of aspects of this invention consists of the combination of a solid substance and an organoaluminum com-pound, the solid substance containing a magnesium-containing inorganic solid ~127799 .

compound and at least one of a titanium and a vanadium compound. The solid substance just referred to above is obtained by `~X
- 6 a -attaching at least one of a titanium compound and a vanadium compound to an inorganic solid carrier, typical of which are metallic magnesium, mag-mesium hydroxide, magnesium carbonate, magnesium oxide and magnesium chlor-ide; double salt, double oxide, carbonate, chloride and hydroxide contain-ing a metal selected from silicon, aluminum and calcium, and magnesium atom. Further, these inorganic solid carriers may be treated or reacted with an oxygen-containing compound, a sulfur-containing compound, a hy-drocarbon or a halogen-containing substance.
Examples of the titanium compound and/or the vanadium compound referred to herein include halides, alkoxyhalides, oxides and halogenated oxides of titanium and/or vanadium. Examples include tetravalnet titanium compounds, e.g., titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monoethoxytrichlorotitanium, diethoxydichlorotitanium, tri-ethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichloro-titanium, diisopropoxydichlorotitanium and tetraisopropoxytitanium;
various titanium trihalides obtained by reducing titanium tetrahalides with hydrogen, aluminum, titanium or an organometallic compound; trivalent titanium compounds, e.g., compounds obtained by reducing various tetra-valent alkoxytitanium halides with an organometallic compound; tetra-valent vanadium compounds, e.g., vanadium tetrachloride; pentavalentvanadium compounds, e.g., vanadium oxytrichloride and orthoalkylvanadate;
and trivalent vanadium compounds, e.g., vanadium trichloride and vanadium triethoxide.
Among the above-exemplified titanium compounds and vanadium com-pounds, tetravalent titanium compounds are specially preferred.
The catalyst used in the process of aspects of this invention con-sists of the combination of a solid substance, which is obtained by attaching a titanium compound and/or vanadium compound to the foregoing carrier, and an organoaluminum compound.

~127 7~

By way of illustrating preferred catalyst systems, mention may .~ - 7a -~lZ 7799 be made of the following solid substances (the R in the following formulae represents an organic radical and X represents halogen) combined with an organoalumin~m compound: MgO-RX-TiC14 system tsee Japanese Patent Publi-cation No. 3514/76), Mq-SiC14-ROH-TiC14 system (see Japanese Patent Publication No. 23864/75), MgC12-Al(OR)3-TiC14 system (see Japanese - Patent PUblications Nos. 152/76 and 15111/77), MgC12-SiC14-R~H-TiC14 sys-tem (see Japanese Patent Laying Open Print No. 106581/74), Mg(OOCR)2-Al(OR)3-TiC14 system (see Japanese Patent Publication No. 11710/77, Mg-POC13-TiC14 system (see Japanese Publication No. 153/76, MgC12-AlOCl-TiCL4 system (see Japanese Patent Laying Open Print No. 133386/76).
In these catalyst systems, a titanium compound and/or a vanadium compound may be used as the addition product with an organocarboxylic acid ester. The foregoing magnesium-containing inorganic compound car-riers may be contacted with an organocarboxylic acid ester before use.
Also, an organoaluminum compound may be used as the addition product with an organocarboxylic acid ester, which would cause no trouble. Furthermore, in e-ery case in the process of aspects of this invention, a catalyst system which has been prepared in the presence of an organocarboxylic acid ester may be used without any trouble.

Various aliphatic, alicyclic and aromatic carboxylic acid esters may be used as organocarboxylic acid ester, among which aromatic carboxy-lic acid9 having 7 to 12 carbon atoms are specially preferred. Examples are alkylesters, e.g., methyl and ethyl esters of benzoic acid, anisic acid and toluic acid.
To illustrate organoaluminum compounds which may be used in the process of aspects of this invention, mention may be made of those repre-sented by the general formulae R3Al, R2AlX, RAlX2, R2AlOR, R~l(OR)X and R3A12X3 wherein R, which may be the same or different, is Cl to C20 alkyl 11277~39 or aryl and X is halogen, for example, triethylaluminum, triisobutyl-alttminum, trihexylalttmintlm, trioctylaluminum, diethylalt~int~t chloride - 8a -llZ7799 ethylaluminum sesquichloride, and mixtures thereof.
m e amount of an organoaluminum compound used in the catalyst used in the process of aspects of this invention is not specially re-stricted, but usually it is in the range of from 0.1 to 1000 mols per mol of a tra~sition metal compound.
In the polymerization reaction, a mixture of ethylene and butene-1 is polymerized in vapor phase in a reactor, which may be a known type, e.g., a fluidized bed or an agitation vessel.
The polymerization reaction conditions involve temperatures usually in the range of from 20~ to 110C., preferably from 50 to 100C., and pressures in the range of from atmospheric pressure to 70 kg/cm G, preferably from 2 to 60 kg/cm G. The lecular weight can be adjusted by changing the polymerization temperature, the lar ratio of catalyst or the amount of comonomer, but the addition of hydrogen into the polymeriza-tion system is re effective for this purpose. Of course, using the pro-cess of aspects of this invention, two or more stage polymerization reac-tions involving different polymerization conditions, e.g., different hydro-gen and comonomer concentrations and different polymerization temperatures may be carried out, without any trouble.
In the process of aspects of this invention, moreover, the fore-going catalyst systems may be contacted with an ~ -olefin before their use in vapor phase polymerization reaction whereby their polymerization activities can be largely improved and a more stable operation is assured than in their untreated condition. In this case, various ~-olefins are employable, preferably those having 3 to 12 carbon atoms and more prefera-bly those having 3 to 8 carbon atoms, for example, propylene, butene-l, pentene-l, 4-methylpentene-1, hexene-l, heptene-l, octene-l, and mixtures thereof. The temperature and time of the contact between the catalyst used _ 9 _ llZ~

in the process of aspects of this invention and an ~ -olefin can be selec-ted in a wide range; for example, the contact treatment may be .~

- 9a -~lZ~79~

applied for 1 minute to 2~ hours at a temperature ranging from 0 to 200C., preferably from 0 to 110C.
The amount of an ~ -olefin to be brought into contact can also be selected in a wide range, but usually it is desired that the contact treatment in question be conducted with an ~-olefin in an amount ranging from 1 g to 50,000 g, preferably from 5 g to 30,000 g, per gram of the aforesaid solid substance and that 1 g to 500 g of the ~ -olefin be reac-ted with the solid substance. The contact pressure may be selected option-ally, but usually it is desired to be in the range of from -1 to 100 kg/cm G.
In the treatment with an o~ -olefin, the total amount of an organoaluminum compound to be used may be combined with the foregoing solid substance and thereafter the resulting mixture may be contacted with the ~ -olefin, or part of the organoaluminum compound may be com-bined with the solid substance and thereafter the resulting mixture may be contacted with the ~ -olefin, while the remaining portion of the organo-aluminum compound may be separately added in the vapor phase polymeriza-tion of ethylene. Furthermore, even in the simultaneous presence of hy-drogen gas or other inert gas, e.g., nitrogen, argon or helium, the cata-lyst used in the process of aspects of this invention may be brought intocontact with an ~'-olefin without causing any trouble.
The amount of butene-l should be in the range of from 1 to 30 mol%, preferably from 2 to 20 mol%, based on the amount of ethylene. Out-side this range, it is virtually impossible to obtain the object product of t~e process of aspects of this invention, namely an ethylene-butene-l copolymer havlng a melt index ranging from -.01 to 10 and a density rang-ing from 0.010 to 0.945. This amount of butene-l to be used can be easily adjusted according to the composition ratio of the vapor phase in 112~ 9 the polymerization vessel.
In the copolymerization according to the process of aspects of - 10 a -X

llZ'^~7~9 this invention, moreover, various dienes may be added as termonomers, e.g., butadiene, 1,4-hexadiene, 1,5-hexadiene, vinylnorbornene, ethylidene-orbornene and dicylopentadiene.
Working examples of the process of aspects of this invention are given below.
Example 1 1 kg of anhydrous magnesium chloride, 50 g of 1,2-dichloro-ethane and 170 g titanium tetrachloride were subjected to ball milling for 16 hours at room temperature in a nitrogen atmosphere to allow the titanium compound-to be attached to the carrier. The resulting solid substance con-tained 35 mg of titanium per gram thereof.
There were used a stainless steel autoclave as a vapor phase polymerization apparatus, a blower, a flow rate adjuster and a dry cyclone to form a loop, and the temperature of the autoclave was adjusted by pas-sing warm water through the jacket.
Into the autoclave adjusted to 80C. were introduced the solid substance prepared above and triethylaluminum at the rates of 250 mg/hr and 50 mmol/hr, respectively, and also introduced were butene-l, ethylene and hydrogen so that the butene-l/ethylene ratio (molar ratio) was 0.10 and the hydrogen gas pressure was 17~ of the total pressure, while the gases in the system were circulated by the blower, under which conditions there was conducted polymerization. The resultinq ethylene copolymer had a bulk density of 0.395, a melt index (MI) of 1.2 and a density of 0.930. It was powdered with most particle sizes falling under the range o 250 to SOO~u. The polymeriæation activity was very high, 204,200 g copolymer/g Ti.
After a continuous operation for 10 hours, the autoclave was opened and its interior was checked to find that the inner wall and the ~12~7~
stirrer were Glean with no polymer adhesion observed. Thus, it is apparent that an extremely stable operation is made possible according to the ;~r gl~ - 11 a -` 1127799 process of aspects of this invention, though it is impossible according to the slurry polymerization shown in Comparative Example 1 below.
m e copolymèr prepared above was formed into a film 400 mm in fold diameter by 30~u thick by an inflation film forming 75mm~ die in a 50 mm~ extruder. The film was superior in strength and had a high transparency with a haze of 5.2% measured according to JIS R6714.
Comparative Example 1 A continuous slurry polymerization was carried out at 85C.
using the same catalyst as that used in Example 1 and in the presence of hexane as solvent.

Hexane as a polymerization solvent containing 5 mg/~ of the solid substance and 1 mmol/~ of triethylaluminum was fed at the rate of 40 ~ /hr, and further introduced were ethylene, butene-l (20 mol~
of ethylene) and hydrogen at the rates of 10 kg/hr, 4 kg/hr and 2Nm /hr, respectively, while a continuous polymerization was conducted on con-dition that the residence time was 1 hour. The resulting copolymer was continuously withdrawn as slurry. In 3 hours after initiation of the polymerization, the polymer slurry withdrawing pipe was obturated, so the polymerization was compelled to be discontinued.
A check was made of the interior of the reactor to find that the hexane layer was emulsified and a large amount of a rubbery poly-mer adhered to the gas-liquid interface and to the withdrawing pipe.
The copolymer prepared above had a bulk density of 0.276, MI
of 0.74 and a density of 0.932.
Example 2 830 g of anhydrous magnesium chloride, 50 g of aluminum oxy-chloride and 170 g of titanium tetrachloride were subjected to ball milling for 16 hours at room temperature in a nitrogen atmosphere.
The resulting solid substance contained 41 mg of titanium per gram thereof.
The solid substance just prepared above and triethylaluminum - 12 a -~12~79~
were fed at the rates of 200 mg/hr and 50 mmol/hr, respectively, and the same polymerization as in Example 1 was carried out at 80C. with the proviso that the butene-l/ethylene ratio in the vapor phase was 0.15 and the hydrogen gas pressuxe was 12% of the total pressure.
After 10 hours of continuous operation, the interior of the autoclave was checked, but there was no polymer adhesion.
The resulting copolymer had a bulk density of 0.420, MI of 0.94 and a density of O.91S. The polymerization activity was very high, 296,000 g ethylene copolymer/g Ti.
In the same manner as in Example 1, the copolymer was formed into a film 400 mm in fold diameter by 30~u thick, which was superior in transparency and in strength.
Comparative Example 2 A solution polymerization was carried out using the same cata-lyst as that used in Example 2 and in the presence of n-paraffin as solvent.
n-Paraffin containing 25 mg/~ of the solid substance prepared in Example 2 and 5 mmol/~ of triethylaluminum was fed at the rate of 40 ~ /hr, and further introduced were ethylene, butene-l and hydrogen at the rates of 10 kg/hr, 6 kg/hr and 550N,~ /hr, respectively, and a - continuous polymerization was carried out at 160C. on condition that the residence time was 1 hour.
The resulting ethylene copolymer had MI of 0.34 and a density of 0.942, and the polymerization activity was 90,000 g copolymer/g Ti.
Thus, it is apparent that in such a solution polymerization, despite the large amount of butene-l used, the density was not lowered so much, and the polymerization activity and efficiency were low.

11~7799 Example 3 830 g of anhydrous magnesium chloride, 120 g of anthracene and 170 g of titanium tetrachloride were subjected to ball milling in the same manner as in Example 1 to give a solid substance which contained ~i ' - 13 a -~l'Z~7799 40 mg of titanium per gram thereof.
Using the same apparatus as that used in Example 1, the solid substance and triisobutylaluminum were fed at 80C. at the rates of 500 mg/hr and 150 l/hr, respectively, and a polymerization was conducted while making adjustment so that the butene-l/ethylene ratio in the vapor phase was 01.4 and the hydrogen gas pressure was 23% of the total pressure.
The polymerization was continued stably for 10 hours, then the autoclave was opened to find that there was no polymer adhesion inside the reactor.
The polymerization activity was 174,000 g copolymer/g Ti, and the resulting polymer had a bulk density of 0.402, MI of 4.7 and a density of 0.920.
The ethylene polymer thus prepared was formed into an inflation film 400 mm in fold diameter .by 30~u thick in the same manner as in Example 1. me film was superior in strength and in transparency with a haze value of 3.8% measured according to JIS K6714.
Example 4 400 g of magnesium oxide and 1300 g of anhydrous aluminum 20 chloride were reacted together at 300C. for 4 hours, then 950 g of the reaction product and 170 g of titanium tetrachloride were treated in the same way as in Example 1 to give a solid substance which contained 30 mg of titanium per gram thereof.
Using the same apparatus as that used in Example l, the solid substance just prepared above and triisobutylaluminum were fed as cata-lyst at the rates of 500 mg/hr and 250 mmol/hr, respectively, and a polymerization was conducted at 80C. while circ~lating a mixed ethylene-butene-l gas containing 12.5 of butene-l based on the amount of ethylene ~,~7 11~ 779~
and also hydxogen gas adjusted to 11~ of the total pressure.
After 18 houxs of continuous operation, the interior of the reactor was checked to find that there was no polymer adhesion.

- 14 a -~lZ779~
The resulting copolymer was composed of oval particles with a narrow particle size distribution, having an average particle diameter of 700 ~ , a bulk density of 0.41~, MI of 0.62 and a density of 0.928, and the polymerization activity was 206,000 g copolymer/g Ti.
The copolymer, without pelletizing, was formed into a hollow bottle having a capacity of 600 cc by means of a high-speed blow molding machine. The bottle had a clear surface without draw-down.

',0 1~

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing an ethylene-butene-1 copolymer hav-ing a melt index ranging from 0.01 to 10 and a density ranging from O.910 to 0.945, which process comprises copolymerizing ethylene and 1 to 30 mol% thereof of butene-1 in a substantially solvent-free vapor phase condition and in the presence of a catalyst consisting of a solid sub-stance and an organoaluminum compound, said solid substance containing a magnesium-containing inorganic solid compound and at least one of a titanium compound and a vanadium compound.

2. A process according to claim 1 in which said at least one of a titanium compound and vanadium compound is a halide, alkoxyhalide, oxide or halogenated oxide of at least one of titanium and vanadium.

3. A process according to claim 1 in which said at least one of a titanium compound and vanadium compound is sued as the addition product with an organocarboxylic acid ester.

4. A process according to claim 1 in which said magnesium-con-taining inorganic solid compound is selected from the group consisting of metallic magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide and magnesium chloride.

5. A process according to claim 1 in which said magnesium-con-taining inorganic solid compound is selected from the group consisting of a double salt, a double oxide, a carbonate, a chloride and an hydroxide containing a magnesium atom and a metal selected from the group consisting of silicon, aluminum and calcium.

6. A process according to claim 1 in which said magnesium-con-taining inorganic solid compound is further treated or reacted with an oxygen-containing compound, a sulfur-containing compound, a hydrocarbon or a halogen-containing substance.

7. A process according to claim 1 in which said magnesium-containing inorganic solid compound is contacted with an organocarboxylic acid ester before use.

8. A process according to claim 1 in which said organoaluminum compound is used as the addition product with an organocarboxylic acid ester.

9. A process according to claim 1 in which said catalyst is prepared in the presence of an organocarboxylic acid ester.

10. A process according to claims 1, 2 or 3 in which said organocarboxylic acid ester is selected from the group consisting of alkyl-esters of benzoic acid, of anisic acid and of toluic acid.

11. A process according to claims 4, 5 or 6 in which said organocarboxylic acid ester is selected from the group consisting of alkyl-esters of benzoic acid, of anisic acid and of toluic acid.

12. A process according to claims 7, 8 or 9 in which said organocarboxylic acid ester is selected from the group consisting of alkyl-esters of benzoic acid, of anisic acid and of toluic acid.

13. A process according to claim 1 in which said copolymerization is carried out at a temperature in the range of from 20° to 110°C. and at a pressure in the range of from atmospheric to 70 kg/cm2?G.

14. A process according to claim 1 in which said copolymerization is carried out in the presence of hydrogen.

15. A process according to claim 1 in which, before initiating said copolymerization, said catalyst system is contacted with an .alpha.-olefin having 3 to 12 carbon atoms for 1 minute to 24 hours at a temperature in the range of from 0° to 200°C. and at a pressure in the range of from -1 to 100 kg/cm2?G.