CA1144695A - Process for preparing copolymers - Google Patents

Abstract

Abstract of the Disclosure Low density copolymers of high molecular weight are obtained by copolymerizing ethylene and .alpha.-olefins in vapor phase using a Ziegler type catalyst.

Description

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This invention relates to a process for preparing low density ethylene copolymers having a high molecular weight.
The production of polyethylenè by polymerization using a catalyst comprising a transition metal compound and an organometallic compound i8 generally conducted by the slurry polymerization process. Generally speaking, the density of polyethylene obtained by such slurry polymerization is limited to not less than 0.945. This value was considered the density limit at which polymer depo~ition of fouling will not occur on the inner wall and on the stirrer in a reaction vessel at the time of polymerization.
Medium or low density polyethylenes with density below 0.945 g/cm3 usually are prepared by the so-called high pressure process using a radical catalyst. Quite recently, however, a high temperature solution polymerization process has been also tried. Further, copolymerizing ethylene with an o~-olefin using a vanadium compound to produce an elastomer ls also known.
However, polymers prepared by the above methods are either crystalline resins or non-crystalline elastomers, and thus their characters are clearly different. These polyolefin plastics and elastomers have theiT
own respective superior characteristics and are employed in Yarious uses.
But for some applications it i8 often required to impart some elastomerlc character to plastics in order to improve their resistance to cracking through environmental stre~s. Conversely elastomers are required to have a strength based on crystallinity. It is well known that if both components are ~kxed together to achieve the desired result, deterioration of the physical propertieæ, such as tensile strength and rigidity is often also a consequence.
Should it be possible to prepare a soft or semi-hard polymer, which is neither a crystalline plastic nor elastomer but has an intermediate ,~
!' ~ ` structure and whicb exhibits a high extensibility, such polymer would fulfil -` the above-nentioned requirement. By blending such polymer into other plastics ~ it i~ then po~sible to impart an elastomeric character to the plastics to - 3~J improve their properties. However, such soft or semi-hard polymer is hitherto 1~ 4g6~

not practically available.
Recently, there have been reports on methods of preparlng such polymer havin~ intermediate physlcal properties, but they have various drawbacks, and attempts to practise them on an industrial scale encounter many problems.
For example, Japanese Patent Publication No. 11028/1971 shows a solution polymerizat~on using an aromatic hydrocarbon solvent in the prepara-tion of ethylene/ ~-olefin copolymers. This method, however, has drawbacks in that the catalyst efficiency is poor, the separation and recovery of the solvent is troublesome because of solution polymerization, and, further, it is difficult to produce high molecular weight copolymers because of restriction on the solution viscosity.
Japanese Patent Publication No. 26185/1972 shows the copoly-merization of ethylene and ~-olefins using a halogenated aliphatic hydrocarbon as a solvent. But this method is disadvanta~eous in that not only is it dif-ficult to prepare high lecular weight copolymers for the same reason as ~en-tioned above, but also large amounts of low molecular weight copolymers are produced, probably because the halogenated hydrocarbon solvent acts as a ~ole-cular weight modifier resutling in sticky surfaces of the articles lded therefrom. In this patent publication a method ls also disclosed using lower hytrocarbons of C3 to C5 as solYents. But in the polymerization using these solvents it 18 necessary to raise the reaction pressure by the Yapor to co~r press and cool the recovered solvent for llquefactlon.
Furthermore, in Japanese Patent Laying Open Print No.
41784/1976 there is disclosed a method of slurry copolymerization between ethylene and butene-l. In thi3 method, however, the polymerization tempesature and the composltion of the starting materials are to be ~aintalned exactly outside the specified range the slurry becomes mllky or porrldge-like, which makes it tlfficult to operate the reactor and transport the slurry.
~ Thus, various drawbacks are encouD~ered in the conventional `~ ~0 method~. For instance, since the catalyst actlvity is low and because of ' ' -1~4g~9S
solution polymerization it is difficult to separate and recover the solvent.
It is difficult to produce high molecular weight copolymers because of restrictions on the solution viscosity. Large amounts of low molecular weight copolymers are produced because of chain transfer with the solvent.
Consequently, high molecular weight polymers are difficult to obtain.
Further, in the case of slurry polymerization, the polymerization tempera-ture and the starting material composition must be strictly controlled in order to maintain the polymer in a slurried condition, as a result, low density copolymers are difficult to obtain.
Thus, according to either of the slurry polymerization or solu-tion polymerization process, soft or semi-hard ethylene/ -olefin copol~mers of low density and high molecular weight have heretofore been very diffi-cult to produce industrially.
In recent years, various studies about the improvement of cata-lyst activity have been made. It is known that if a transition metal is attached to a magnesium-containing solid carrier such as, for example, MgO, Mg(OH)2, MgC12, MgCO3, or Yg)OH)Cl, and then combined with an organometallic compound, the resulting catalyst system can serve as a remarkably high activity catalyst in the polymerization of olefins. It is also known that the reaction product of an organomagnesium compound such as, for e~ample, RMgX, R2Mg or RMg(OR) and a transition metal compound can serve as a high polymerization catalyst for olefins ~see, for example, Japanese Patent Publications Nos. 12105/1964, 13050/1968 and 9548/1970 and Belgian Patent No. 742,112).
; However, even in the slurry polymerization or solution polymeri-zation carried out using such a high activity catalyst with carrier in an effort to obtain low density polymers, the foregoing drawbacks have not been remedied.
Thus, it is an object of this invention to provide a new process ~A -3_ ~i44696 which solves these problems.
It is another object of this invention to overcome various pro~lems associated with solution polymerization or slurry polymerization, such as, low catalyst cativity, low bulk density, polymer adhesion or agglomeration.

A further ob~ect is to provide a process for preparing low density, high lecular weight ethylene/,C-olefin copolymers having improved physical properties.
It is yet another ob~ect of this invention to provide a vapour phase polymerization process for ethylene and,~-olefines, which process as a whole is simple, performs the polymerization reaction in a stable manner, and wherein the catalyst removing step is omitted.
Accordingly, the present invention provides a process for preparing a soft or semi-hard ethylene/~-olefin copolymer having an intrinsic viscosity of between 3.0 to 10 d ~ g measured in decalin at i35C and a density of between 0.850 to 0.910, which process comprises copolymerizing ethylene and between 4 to 250 mole% based on the amount of ethylene of an ~-olefin in a substantially solvent-free vapor phase condition, at a temperature of between to 80 C, at a hydrogen concentration in the Yapor phase of between 0 to 5 moleX and in the presence of a catalyst, said catalyst comprising a solid substance an an organoaluminum compound, and said solid substance containing a magnesium-containing inorganic solid carrier and at least one member selected from the group consisting of a titanium compound and a vanadium compound.
By a variant of the aboye process, the d~-olefin is an O~-olefin haYing 3 to 8 carbon atoms.
By another Yariant, theAC-olefin is used in the amount of 5 to 100 moleZ based on the amount of ethylene.
By another Yariant, the titanum compo~nd is a halide, alkoxyhalide or halogenated oxide of titanium.
By another variant, the yanadium compound is a halide, alkoxyhalide or halogenated oxide of Yanadium.
By another Yariant, the organoaluminum compound is a com-pound represented by the general formula R3Al, R2AlX, RAIX2, R2AlOR, RAl(OR)X
or R3A12X3 wherein R, which may be alike or different, is a Cl to C20 alkly ~30 group or aryl group and X is a halogen atom.

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By another variant, the catalyst is prepared in the presence of an organocarboxylic acid ester.
By another variant, the catalyst is treated with ethylene and/or an_~-olefin~and thereafter used in the copolymerization reaction.
More specifically, a soft or semi-hard ethylene/ ~-olefin copolymer is proYided having an intrinsic Yiscosity of between 3.0 to 10 d /g measured in decalin at 135C and a density of between 0.850 to 0.910, prepared by copolymerizing ethylene and between 4 to 250 le% based on the amount of ethylene of an ~-olefin in a substantially solvent-free Yapor phase condition, at a temperature of between 10 to 80C, at a hydrogen concentration in the vapor phase of between 0 to 5 mole% and in the presence of a catalyst, said catalyst comprising a solid substance and an organoaluminum compound, and said solid substance containing a magnesium-containing inorganic solid carrier and at least one member selected from the group consisting of a titanium and a vanadium compound.
According to this invention, ethylene and 4 to 250 moleX
based on the amount o~ ethylene of an ~ -olefin~are copolymerized in a sub-stantially solvent-free ~apor phase condition, at a temperature o~ 10 to 80C, at a hydrogen concentration in the vapor phase of 0 to 5 moleX and in the presence of a catalyst which comprises a solid substance and an organo-aluminum compound, the solid substance containing a magnesium-containing in-organic solid carrier and a titanium compound and/or a Yanadium compound, a soft or semi-hard ethylene/ ~-olefin copolymer is obtained haYing an intrins~c YiS-osit~ of 3.0 to 10 d ~ g measured in decalin at 135C and a density of 0.850 to 0.910.
It has been found that if a Yapor phase polymerization is carried out according to the process of this inYentlon, that is,-using ethylene and anoC-olefin in a quantitiatiYe ration within the specified range, and using a catalyst comprising a solid substance andan organoaluminum compound, which 30~ solid substance contains a magnesium-containing inorganic solid carrier snd a il4469ti titanium compound and/or a vanadium compund, then the polymerization is effected in an extremely high acti~ity and the resulting polymer has a high lecular weight, is highly sticky and is low in density, while the production ratio of coarse and ultra-fine particles is reduced, so that particle properties are improved. Furthermore, the bulk density is high, the polymer adhesion to the reactor and agglomeration of polymer particles are minimized. Thus, the vapor phase polymerization reaction can be performed in an extremely stable manner.
It is surprising that utilizing the process of this invention, not only does it become possible to carry out a vapor phase polymerization reaction extremely smoothly, but also ethylene copolymers of hi~h molecular weight and extremely low density are easily obtained.
In theprocess of this invention, the ~-olefin copolymerized with ethylene ad~usts the density and molecular weight of copolymer, and the resulting copolymer is superior in transparency, outer appearance and luster, and i8 a highly flexible and rubber-like elastic at low temperatures, as well as at room temperature.
In addition to such a high flexibility, the strength of copolymers obtained according to the process of this invention is equal to or even higher than that of ordinary polyolefin resins. Further, they have im-proved weathering resistance, resistance to chem~cals and electrical charac-ter~stics such as dielectric loss, break-down voltage and resistivity because they contain few unsaturated bonds, residual catalysts or other impurities.
Also, as far as resistance to impact and to cracking due to enYironmental stress , the copolymers prepared according to the process of this inYentiOn exhibit excellent characteristics, which allow them to be formed into films, sheets, hollow containers, electric wires and Yarious other products by the existing forming methods such as extrusion molding, blow molding, in~ection molding, press forming and vacuum ~orming. They may be used in many applications.
~ur~hermore, since the copolymers obtained according to the process of this in~ention contain olefins as a component, they are very si~ilar il44695 in composition to polyolefin resins. In addition, because of a low crystal-linity, they are con~atible with other polyolefin resins, particularly with high- and low-density polyethylenes, polypropylenes and ethylene-vinyl acetate copolymer, so their blending into these resins can improve properties of the latter such as resistance to impact, to tear, to cold and to cracking due to environmental stress.
For a more complete understanding of the in~ention, the fol-lowing detailed description of example embodiments thereof is given.
The catalyst system used in the process of this invention combines a solid substance with an organoaluminum compound which solid substance contains a magnesium-containing inorganic solid carrier and a titanium compound and/or a vanadium compound. As the magnesium-containlng inorganic solid carrier are mentioned, for example, metallic magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, further double salts, double oxides, carbonates, chlorides and hydroxides, which contain magnesium atom and a metal selected from silicon, aluminum and calcium, and still further these inorganic solid compounds after treatment or reaction with an oxygen-containing compound, a sulfur-contalning compound, an aromatic hydrocarbon or a halogen-containing \' ' ', .

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substance. And to the inorganic solld carrier exemplifled above is attached a titanlum compound and/or a vanadium compound in known manner.
As the above mentioned oxygen-containing compound are exemplified water; organic oxygen-containing compounds such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, and acid amides;
and inorganic oxygen-containing compounds such as metal alkoxides and metal oxyhalides. As the sulfur-containing compound are exemplified organic sulfur-containing compounds such as thiol and thioethers; and inorganic sulfur-containing compounds such as sulfur dioxide, sulfur trloxlde and sulfuric acid. As the aromatlc hydrocarbon are exemplified mono- and poly-cyclic aromatlc hydrocarbons such as benzene, toluene, xylenes, anthracene and phenanthrene. As the halogen-contalnlng substance are exempllfled compounds such as chlorine,hydrogen chloride, metal halides and organic halides.
lS By way of illustretlng the titanium compound and/or vanadium compound, mention may be made of halides, alkoxyhalides and halogenated oxides of titanium and/or vanadium. Preferred titanium compounds are of the general formula Ti(OR~nX4_n wherein R is alkyl, aryl or aralkyl having 1 to 24 carbon atoms and n is 0 S n 5 4, and also trivalent tltanlum compounds obtained by reducing these tetravalent titanium compounds with for example hydrogen, tltanium, aluminum or an organometallic compound of a Group I-III metal in the Periodic Table. Examples of titanium compounds and vanadlum compound are tetravalent titanium compounds such as titanlum tetrachloride, titanium tetrabromide, titanium tetraiodide, monoethoxytrichlorotltanium, diethoxydichlorotitanium, triethoxymono-chlorotitanium, tetraethoxytitanlum, monolsopropoxytrlchlorotitanium, dii~opropoxydichlorotitanlum and tetraisopropoxytltanlum; various titanium trihalides obtained by reducing titanlum tetrahalldes with hytrogen~ aluminum, titanium or an organometallic compound; trivalent titanium compounds such as compounds obtained by reducing various tetravalent alkoxytitanium halldes with an organometallic compound;
tetravalent vanadium compounds such as vanadium tetrachlorlde;
pentavalent vanadium compounds such as vanadium oxytrichloride and orthoalkyl vanadate; and trivalent vanadium compounds such as vaDadium trichloride and vanadium triethoxide.
Tetravalent titanium compounds are particularly preferred among the above-enumerated titanium compounds and vanadium compounds.
; The catalyst used in the invention comprises the combination of a solid substance which contains the foregoing solid carrier and a titanium compound and/or a vanadium compound, with an organoaluminum compound.
Examples of such catalyst are combinations of organoaluminum compounds and the following solid substances (in the following formulae R represents an organic radical and X represents a halogen atom):
MgO-RX-TiC14 system (see Japanese Patent Publication No.3514/1976~, Mg-SlC14-ROH-TlC14 system (see Japanese Patent Publication No.23864/1975), NgC12-Al(OR)3-TiC14 system (see Japanese Patent Publications Nos.152/1976 ant 15111/1977), MgC12-SiC14-ROH-TiC14 system (see Japanese Patent Laying Open Print No.106581/1974), MgtOOCR)2-Al~OR)3-TiC14 system (see Japsnese Patent Publication No.11710/1977), Mg-POC13-TiC14 system (see Japanese Patent Publication No.153/1976) and MgC12-AlOCl-TiC14 system (see Japanese Patent Publication No.15316/1979).
In these catalyst systems, a titanium compound and/or a vanadium compound may be used as an adduct with an organocarboxylic acid ester, and the foregoing magnesium-containing inorganic solid carrier may be used after contact with an organocarboxylic acid ester. Also, using an organoaluminum compound as an adduct with an organocarboxylic acid ester caufie-Q no trouble. Further, in all possible cases in this invention, a catalyst 8ystem prepared in the presence o~ an organocarboxylic acid ester may be used without causing any trouble.
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As the organocarboxyllc acld ester there may be used esters of various aliphaticJalicyclic and aromatic carboxylic aclds, preferably aromatic carboxylic acids of C7 to C12, for example, alkyl esters such as methyl and ethyl of benzoic acid, anisic acid and toluic acid.
Examples of the organoaluminum compound used in this invention are those represented by the general formulae R3Al, R2AlX, RAlX2, R2AlOR, RAl(OR)X and R3A12X3 wherein R, which may be alike or different, is Cl to C20 alkyl or aryl and X is halogen, such as triethylaluminum, triiso-butylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, and mixtures thereof.
In the process of this invention, no special limltatlons are placed on the amount of the organoaluminum compound to be used, but usually it may be employed in an amount of 0.1 to 1000 moles per mole of the transltion metal compound.
In the process of this invention, moreover, by contacting the foregoing catalyst system with an ethylene and/or a-olefin and thereafter using it in the vapor phase polymerization reaction, the polymerization activity can be improved to a large extent and the operation can be performed more stably than in the case where such pre-treatment i8 not applied. And as the a-olefin used in such pre-treatment there may be employed various a-olefins, preferably those of C3 to C12 and more preferably those of C3 to Cg. Examples are propylene, butene-l, pentene-1,4-methylpentene-1, heptene-l, octene-l, and mixtures thereof. The temperature and duration of the contact between the catalyst of this invention and ethylene and/or an a-olefin can be chosen over a wide range; for example, the contact trestment may be performed for 1 minute to 24 hours at 0 to 200C, preferably 0 to 110C. The amount of ethylene and/or the a-olefin to be contacted can also be chosen over a wide range, but usually it i8 desirable that the catalyst of th$6 inventlon be treated wlth lg to -` ~,~469S' 50,000g, preferably 5g to 30,000g, per Rram of the foregoing solld substance of ethylene and/or C~-olefin to allow lg to 500g, preferably lg to lOOg, of ethylene andlor the a-olefln to be rescted per gram of the solid substsnce. The said contact treatment may be done at any desired pressure, but preferably -1 to 100 kg/cm2 G.
The aforesaid pre-treatment with ethylene and/or an ~-olefin may be carried out by first combining the total amount of the organoaluminum compound to be used with the foregoing solid substance and then contacting with ethylene and/or the ~-olefin, or alternatively, by first combining part of the organoaluminum compound wlth the solid substance and then contacting with ethylene and/or gaseous ~-olefin and adding the remaining organoaluminum compound separately in the vapor phase polymeriz-ation. During the contact between the catalyst and ethylene and/or an a-olefin there may be present hydrogen gas or other inert gas such a~
nitrogen, argon or helium.
In this invention there is conducted copolymerization of ethylene with an ~-olefin in the presence of a catalyst comprising a solid substance and an organoaluminum compound, which solid substance contains a magnesium-containing inorganic solid carrier and a titanium compound and/or a vanadium compound.
As the C~-olefin to be used in the copolymerization reaction, those of C3 to C8 are preferred, for example, propylene, butene-l, hexene-l, 4-methylpentene-1, and octene-l. These ~-olefins should be used in amounts ranging from 4 to 250 mole%, preferably from 5 to 100 moleX, based on the amount of ethylene. Outside this range it is impossible to obtain the ob~ect product of this invention, namely soft or semi-hard ethylene/ C~-olefin copolymers having an intrinsic viscosity of 3 to 10 d~/g, preferably 3.7 to 8 d~/g, measured in decalin at 135C
and a density of 0.850 to 0.910. The amount of CX-olefins to be used can be ad~usted easily by changing the composition ratio of the vapor .~

`` 1144~5 pha~e in the polymerlzatlon vessel.
In the process of thls invention, moreover, various dienes may be added in the copolymerization as termonomers, such as butadiene, 1,4-hexadiene, 1,5-hexadiene, vinyl norbornene, ethylidene norbornene and dicyclopentadiene.
The polymerization reaction in this invention is carried out in a substantially solvent-free vapor phase condition. ~s the reactor to be used, there may be employed known ones such as fluidized bed and agitation vessel.
The temperature of lhe polymerization reaction is in the range of from 10 to 80C, preferably from 20 to 70C, and the pressure thereof in the range of from atmospheric pressure to 70 kg/cm2 G, preferably from 2 to 60 kg/cm2 G.
In this invention, moreover, it i8 necessary to add hydrogen so that the hydrogen concentration in the vapor phase is in the range of from O to 5 mole~. Outside this condition it i8 impossible to obtain the ob~ect copolymers of this invention.
It goes without saying that using the process of this invention there can be conducted without any trouble two or more stage polymerization reactions involving different polymerization conditions such as different hydrogen and comonomer concentrations and dlfferent polymerlzation temperatures.
~orking examples of this invention are given below, but it is to be understood that these examples are for illustration only to work the invention and are not intended to restrict the invention.

Example 1 1000 g. of anhydrous magnesium chloride. 50 g. of 1,2-dichloroethane and 170 g. of titanium tetrachloride were sub~ected to ball milllng for 16 hours at room temperature in a nitrogen atmosphere to allow the titanium compound to be supported on the carrier.

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The resulting solid gubstance contained 35 mg. of tltanium per gram thereof.
As an apparatus for the vapor phase polymerization there was used a stainless steel autoclave, and with a blower, a flow rate ad~usting valve and a dry cyclone for separating the resulting polymer being provided to form a loop. Temperature control for the autoclave was effected by passing warm water through the Jacket.
The polymerization temperature was set at 40C, and the above solid substance and triethylaluminum were charged into the autoclave at the rates of 250 mg/hr and 50 mmol/hr, respectively, and there was made polymerizatlon while ad~usting the composition (mole ratio) of the gases fed to the autoclave wlth the blower so that ethylene was 69% and butene-l ¦
31X.
The resulting polymer had an intrinsic viscosity measured in decalin at 135~ (in the following comparative and working examples this will be referred to simply as l'intrinsic viscosity") of 4.5 d ~g, a bulk denslty of 0.38 and a density of 0.891. The polymerlzation activity was very high, 312,000 g.polyethylene/g.Ti.
After continuous operation for 10 hours, the polymerization was stopped and the interior of the autoclave was checked to find that the polymer did not adhere at all to the inner wall, stirrer and polymer withdrawing pipe. In the slurry polymerization shown in the following Cparative Example 1 it was impossible to continue operation stably for a long time, while the results obtained in the above working example clearly show that according to the process of this invention it is possible continue operation for an extended period of time and that extremely stably.

Comparative Example 1 Using the same catalyst as in Example 1 there was made a continuous slurry polymerization at 40~C while feedin8 5 mgl~ of the llg469S
solid substance, 1 mmol/l of triethylaluminum, 40 ~/hr of hexane as a solvent, 8 kg/hr of ethylene, 14.0 kg/hr of butene-l (86 mol% of ethylene) and 3 Nm3/hr of hydrogen.
The resulting polymer was in an intermediate form between slurry and solution and the polymer particles were swollen from the initial stage of polymerlzation, and the hexane layer was a viscous solution. After 2 hours, the slurry withdrawing pipe was blocked so the polymerization was compelled to be discontinued. The interior of the reactor was checked to find that a large amount of the polymer adhered to the inner wall and the stirrer.
The intrinsic viscosity and density of the re~ulting polymer were 4.1 d~/g and 0.903, respectively. Thus, despite of a large amount of butene-l added as a comonomer, the density of the polymer was not sufficiently lowered, and the continuous polymerization tid not proceed stably. It is apparent that this comparative example is an example of a very disadvantageous polymerization.

Example 2 Polymerization was made in the same manner as in Example 1 except that the polymerization temperature was set at 30C and that the gases fed to the autoclave were ethylene, butene-l and hydrogen in the proportions (mole ratios) of 75%, 23X and 2X, respectively.
After continuous operation for 10 hours, the polymerization was stopped and the interior of the reactor was checked to find that there was no adhesion of polymer.
The resulting polymer had an intrinsic viscoslty of 5.1 d~g, a bulk density of 0.40 and a density of 0.901. The polymerization activity was 265,000 g.polymer/g.Ti.

Example 3 - 830 g. of anhydrous magnesium chloride, 120 g. of anthracene -` 114469S

and 180 g. of titanium tetrachloride were subiected to ball milling in the same manner as in Example l to give a solid substance, which contained 40 mg. of titanium per gram thereof~
Using the same apparatus as in Example 1 there were fed the above solid substance and triisobutylaluminum at the rates of 5.00 mg/hr and 150 mmol/hr, respectively, and there was made a continuous polymerization at 20C while ad~usting the composition (mole ratio) of the gases fed to the autoclave so that ethylene was 77X and propylene 23%.
After continuous operation for lO hours, the polymerizatlon was stopped and the interior of the reactor was checked to find that there was no adhesion of polymer.
The resulting polymer had an intrinsic vlscosity of 4.7 ~ g, a bulk density of 0.39 and a density of 0.895. The polymerization activity was 127,000 g.polymer/g.Ti.

Example 4 A continuous polymerization was carried out in the same way as in Example 3 except that butene-l was used in place of propylene, that the ratio ~ le ratio~ of ethylene and that of butene-l in the vapor phase were ad~usted to 61X and 39X, respectively, and that the polymerlzation temperature was set at 50C.
After continuous operation for lO hours, the polymerizatlon was stopped and the interior of the reactor was checked to find that there was no adhesion of polymer.
The resulting polymer had an intrinsic viscosity of 3.7 d~g, a bulk density Qf 0.39 and a density of 0.886. The polymerization activity waY 405,0~0 g.polymer~g.Ti.

Example 5 180 g. of titanium tetrachloride and 950 g. of the reaction product resulting from reactlon at 300~C for 4 hours of 400 g. magnesium .. .. . .

~44695 oxide and 1.3 kg. aluminum chloride were sub~ected to ball milling in the same way as in Example 1 to give a solid substance containing 39 mg.
of titanium per gram thereof.
Using the same apparatus as in Example 1 there were fed the above solid substance and diethylaluminum chloride at the rates of 500 mg/hr and 250 mmol/hr, respectively, and a continuous polymerization was conducted at 40C while ad~usting the composition (mole ratio~ in the vapor phase so that ethylene was 64X and butene-l 36X.
After continuous operation for 10 hours, the polymerization was stopped and the interior of the reactor was checked to find that there was no adhesion of polymer.
The resulting polymer had an intrinsic viscosity of 5.3 d~lg, a bulk density of 0.37 and a density of 0.891. The polymerization activity was 105,000 g.polymer/g.Ti.

Example 6 A continuous polymerization was carried out in the same way as in Example 5 except that triethylaluminum was used in place of diethylaluminum chloride, that butene-l was substituted by propylene and that the ratio ~mole ratio) o`f ethylene and that of propylene in the vapor phase were ad~usted to 69X and 31X, respectively.
After continuous operation for 10 hours, the polymerization was stopped ant the interior of the reactor was checked to find that there was no adhesion of polymer.
The resulting polymer had an intrinsic vi~cosity of 4.8 d~/g, a bulk density of 0.40 and a density of 0.908. The polymerization activlty was 335,000 g.polymer/g.T1.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for preparing a soft or semi-hard ethylene/?-olefin copolymer having an intrinsic viscosity of between 3.0 to 10 d?/g measured in decalin at 135°C and a density of between 0.850 to 0.910, which process comprises copolymerizing ethylene and between 4 to 250 mole% based on the amount of ethylene of an ?-olefin in a substantially solvent-free vapor phase condition, at a temperature of between 10° to 80°C, at a hydrogen concentration in the vapor phase of between 0 to 5 mole% and in the presence of a catalyst, said catalyst comprising a solid substance and an organoaluminum compound, and said solid substance containing a magnesium-containing inorganic solid carrier and at least one member selected from the group consisting of a titanium com-pound and a vanadium compound.

2. The process as defined in claim 1, in which said .alpha.-olefin is an .alpha.-olefin having 3 to 8 carbon atoms.

3. The process as defined in claim 1, in which said .alpha.-olefin is used in an amount of 5 to 100 mole% based on the amount of ethylene.

4. The process as defined in claim 1, in which said titanium compound is a halide, alkoxyhalide or halogenated oxide of titanium.

5. The process as defined in claim 1, in which said vanadium compound is a halide, alkoxyhalide or halogenated oxide of vanadium.

6. The process as defined in claim 1, in which said organoaluminum compound 18 a compound represented by the general formula R3Al, R2AlX, RAlX2, R2AlOR, RAl(OR)X or R3Al2X3 wherein R, which may be alike or different, is a C1 to C20 alkyl group or aryl group ant X is a halogen atom.

7. The process as defined in claim 1, in which said catalyst is prepared in the presence of an organocarboxylic acid ester.

8. The process as defined in claim 1, in which said catalyst is treated with ethylene and/or an .alpha.-olefin and thereafter used in the copolymerization reaction.

9. A soft or semi-hard ethylene/.alpha.-olefin copolymer having an intrinsic viscosity of between 3.0 to 10 d?g measured in decalin at 135°C and a density of between 0.850 to 0.910, prepared by copolymerizing ethylene and between 4 to 250 mole% based on the amount of ethylene of an .alpha.-olefin in a substantially solvent-free vapor phase condition, at a tem-perature of between 10° to 80°C, at a hydrogen concentration in the vapor phase of between 0 to 5 mole% and in the presence of a catalyst, said catalyst comprising a solid substance an an organoaluminum compound, and solid substance containing a magnesium-containing inorganic solid carrier and at least one member selected from the group consisting of a titanium compound and a vanadium compound.