CA1261545A - Process for producing ethylene copolymer - Google Patents

Abstract

Abstract of the Disclosure An improved process for producing an ethylene copolymer composed of a major proportion of ethylene and a minor proportion of an alpha-olefin having 3 to 10 carbon atoms and having a density of 0.900 to 0.945 g/cm3 and an ethylene content of 85 to 99.5 mole%. The use of a titanium catalyst component (A) which meets a parametric combination of specific requirements is es-sential in this process. The process can industrially advantageously give a low to medium density ethylene copolymer of high quality with high productivity while advantageously circumventing the operational troubles which have been difficult to avoid by conventional pro-cesses.

Description

Title: PROCESS FOR PRODUCING ETHYLENE COPOLYMER

This invention relates to a process for produc-ing an ethylene copolymer having a density of 0.900 to 0.9~5 g/cm3 from a major proportion of ethylene and a minor proportion of an alpha-olefin having 3 to 10 carbon atoms using a catalyst essentially comprising a specific titanium catalyst component. It is an improved process by which a low to medium density ethylene copolymer having hiyh quality can be produced industrially advan-tageously with high catalytic activity and hi~h produc-tivity per polymerization vessel by an industrially easy operation.
It is known that copolymeri2ation of ethylene with a minor proportion of an alpha-olefin with a Ziegler catalyst gives an ethylene copolymer having the same density as high-pressure polyethylene. Generally, it is advantageous to employ a high-temperature solution-polymerization process in which the polymerization is carried out by using a hydrocarbon solvent at a tempera-ture above the melting point of the resulting copolymer because the polymerization operation is easy. However, attempts to obtain a polymer having a sufficiently high molecular weight result in higher viscosities of the polymer solution, and the polymer concentration in the polymer solution should be lowered. Accordingly, the process has the de~ect that the productivity of the copolymer production per polymerization vessel neces-sarily becomes low.
On the other hand, when it is desired to obtain the aforesaid low~density ethylene copolymer using known catalysts by the slurry polymeriation method Erequently used in the production of high-density polyethylene, the Copolymer is frequently liable to dissolve or swell in the polymer solution, resulting in the rise of the vis-cosity of the polymer solution, the adhesion o~ the polymer to the polymerization vessel walls and the decrease of the bulk density of the polymer. Accordingly, this method has the defect that the slurry concentration cannot be increased, and it cannot be operated continu-ously for a long period of time. Furthermore, the result-ing copolymer becomes sticky, and its quality is affected.
It has been found that the aforesaid technical defects or troubles are especially serious in the pro-duction of low to medium density ethylene copolymers from a major proportion of ethylene and a minor proportion of an alpha-olefin having 3 to 10 carbon atoms.
Investigations of the present inventors have shown that the aforesaid technical defects or troubles are efipecially great in the production of ethylene co-lS polymers having a density of 0~900 to 0.945 g/cm3 of ethylene as a main component and a minor amount of an alpha olefin having 3 to 10 carbon atoms as a comonomer which can give film products having excellent trans-parency and heat-sealing property.
Investigations of the present inventors have shown that in the production of the above ethylene co-polymers by the slurry polymerization method, the result-ing solid polymer is liable to swell in the reaction solvent and to assume an irregular shape far from a desirable shape such as a sphere or the like, and there-fore if the concentration of the polymer in the polymeri-zation system is increased, the polymerization system assumes a porridge-like slurry which makes it difficult to perform a polymerization operation permitting uniform polymerization. It has further been found that it is impossible to avoid the formation of a substantial amount of an ethylene coplolymer easily soluble in hydrocarbon solventsr which is indicated, for example, as the pro-portion of the hexane-soluble portion in Examples and Comparative Examples given hereinafter, and consequently the viscosity of the copolymer solution increases unduly.

These technical defects attributed to the poor slurry properties during the polymerization have been found to be difficult to circumvent.
Thus, because of the poor slurry properties during slurry polymerization for the production of the specific ethylene coplolymers, the slurry concentration of the copolymerization system cannot be increased, and therefore, the desired ethylene copolymer cannot be produced with high productivity. Furthermore, increasing the slurry concentration of the copolymerization system causes various troubles such as an abrupt reduction in stirring efficiency, blockage of pipes for conveying the slurry, the reduced efficiency of separating the co-polymer from the polymerization solvent in a decanter, and the increased load of energy required to dry the separated copolymer~
When a vapor-phase polymerization method is used instead of the slurry polymerization method, it is likewise impossible to avoid the formation of a sub-stantial amount of an ethylene copolymer easily solublein hydrocarbon solvents. Moreover~ since the ethylene polymer shows undesirable tackiness in the vapor phase copolymerization system, the copolymer particles are agglomerated in the vapor-phase polymerization reaction zone, and a stable fluidized bed becomes difficult to form. Furthermore, it is difficult to circumvent blockage of that part of the polymerization vessel which is near a port for withdrawing the resulting ethylene copolymer~
No proposal has yet been known of using the titanium catalyst component specified in the process of this invention with a view to overcoming the aforesaid technical defects or troubles which constitute an es-pecially important technical problem in the production of an ethylene copolymer having a density of 0.900 to 0.945 g~cm3 and composecl of a major proportion of ethylene and a minor proportion of alpha-olefin having 3 to 10 carbon atoms.
Some prior proposals are known of polymerizing or copclymerizing olefins in the presence of a catalyst composed of a titanium catalyst component, which is the reaction product of a hydrocarbon solvent-insoluble magnesium/aluminum solid comple~ derived from a liquid magnesium compound and an organoaluiminum compound, and an oryanoaluminum compound catalyst component. However, no proposal has been known of covercoming the aforesaid technical defects or troubles in the production of the above-specified ethylene coplolymer.
For example, Japanese Laid-Open Patent Publi-cation No. 11908/1981 (corresponding to European Laid-lS Open Patent Publication No. 22675) proposes a process forpolymerizing or copolymerizing olefins in the presence of a catalyst which can embrace the aforesaid catalyst composed of the titanium catalyst component and the organoaluminum compound catalyst component. This pro-posal, however, does not at all refer to the presence ofthe aforesaid technical problem in the production of the specif ic ethylene copolymer and its solution. All of the working examples given in this patent document are direct-ed to the polymerization of propylene. Naturally, there-fore, this patent publication neither describes norsuggests the parametric combination of the requirements ~i) to (iv) of this invention to be described in detail hereinafter. It neither gives a specific disclosure of any one of these requirements. In particular, as regards the requirement (iii), the above patent document states that the Ti/Mg (atomic ratio) is at least 1, usually about 5 to about 200, especially about 10 to about 100.
As will be shown by Comparative Example 5, the use oE the Ti/Mg atomic ratio which does not meet the requirement 3s (iii) cannot achieve the unexpected and excellent improv-ing effect by the process of this invention.

Japanese Laid-Open Patent Publication No.
1~9206/1983 (corresponding to European Laid-Open Patent Publication No. 93494) also proposes a process which comprises polyMeriæing or copolymerizing olefins in the presence of a catalyst which can embrace the catalyst composed of a titanium catalyst component, which is the reaction product of a hydrocarbon solvent-insoluble maynesium/aluminum solid complex derived from a liquid magnesium compound and an organoaluminum compound, and an organoaluminum compound catalyst component. This patent document neither rePers to the presence of the aforesaid technical problem in the production of the aforesaid specific ethylene copolymer and its solution. All of the working examples in this patent document are directed to homopolymerization of ethylene/propylene or butene-l. In thi~; proposal, too, it is natural that no specific dis-closure is made of the parametric combination of the requirements (i) to ~iv~ of the present invention or of any of these requirements individually.
It is an object of this invention therefore to provide a process for producing an ethylene copolymer having a low to medium density and composed of a major proportion of ethylene and a minor proportion of an alpha-olefin having 3 to 10 carbon a~oms, which can overcome the aforesaid technical problem in the pro-duction of low to medium density ethylene copolymers.
Disclosure of the Invention This invention i8 a process for producing an ethylene copolymer comprising a major proportion of ethylene and a minor proportion of at least one alpha-olefin which comprises copolymerizing ethylene with at least one alpha-olefin having 3 to 10 carbon atoms in the presence of a catalyst composed of ~A) a titanium catalyst component which is the reaction product of ~A-l) a hydrocarbon solvent-insoluble magnesium/aluminum solid complex derived from a liquid magnesium compourld and an organoaluminum compound, with (A-2) a tetra-valent titanium catalyst compound, and ~B~ an organoaluminum compound catalyst com-s ponent;
wherein ~i) the titanium catalyst component ~A) con-tain~ 10 to 100 ~, based on the entire Ti in the com-ponent, of Ti of a lower valency state than a valence of ~, ~ii) the solid complex (A-l) contains 0~01 to 0.5 g-equivalent, per Mg atom, of a hydrocarbon group R2 having reducibility and 0.5 to 15 parts by weight, per part by weight of Mg, of an organic group ORl (where R represents a hydrocarbon group) having no reducibility, ~ the titanium catalyst component (A) is a reaction product obtained by reacting the solid complex (A~l) and the tetravalet titanium compound (A-2) under such conditions that the Ti/Mg atomic ratio of (A-l) and (A-2) is from 0.01 to 0.6, an~
(iv) the resulting ethylene copolymer has an ethylene content of 85 to 99.5 mole % and a density of O.90o to 0.945 g/cm3.
Investigations of the present inventors have shown that by satisfying the parametric combination of the requriements ~i) to ~iv), there can be provided an improved process by which the technical problem stated in detail hereinbefore can be overcome industrially advan-tageously, it is possible to circumvent the operational troubles which are attributed to the increased formation of a hydrocarbon-soluble copolymer shown in Examples and Comparative ~xamples given below as the hexane-soluble portion and the worsened characteristics of the resulting polymer particles and which have been difficult hereto-fore to avoid, a copolymer having a narrow composition distribution can be p~oduced, and a low to medium (0.9OQ
to 0.945 g/c~3, especially 0.910 to 0.945 g/cm3~
ethylene copolymer of high quality capable of being formed into films and other articles having excellent transparency, antiblocking property and heat sealing property can be produced advantageously on an industrial scale with high catalytic activity and high productivity per polymerization vessel by an industrially easy oper-ation.
The process of this invention has also been found to have the advant~ge that in a process, such as vapor-phase polymerization, in ~hich all of the resulting copolymer be¢ornes a product~ such excellent molded arti-cles can be obtained, and during catalyst preparation, the efficiency of utilizing the raw materials is high and the waste liquor can be easily treated.
In the process of this invention, an ethylene copolymer containing a major proportion of ethylene and a minor proportion of at least one alpha-olefin is produced by copolymerizing eth~lene with at least one alpha-olefin having 3 to 10 carbon atoms, preferably 4 to 10 carbon atoms, in the presence of the catalyst composeed of the titanium catalyst component ~A) and the organoaluminum compound catalyst component ~B) so that the requirements ~i), ~ii), ~iii) and ~iv) are satisfied in combination.
The liquid magnesium compound utilized in the formation of the titanium catalyst component ~A) may, for example, be a solution of a magnesium compound in a hydrocarbon, an electron donor or a mixture of both, or a melt of a magnesium compound.
Examples of the magnesium compound include magnesium halides such as magnesium chloride, magnesium bromidet magnesium iodide and magnesium fluoride; alkoxy magnesium halides, preferably Cl-C20 alkoxy magnesium halides, such as methoxy magnesium chloride, ethoxy maynesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride and octyl magnesium chloride; arylo~y magnesium halides, preferably C6-C30 aryloxy magnesium halides, such as phenoxy magnesium chloride and methyl-phenoxy magnesium chloride; alkoxy magnesiums, preferably Cl-C20 alkoxy magnesiums, such as ethoxy maqnesium, isopropoxy magnesium, butoxy magnesium and octoxy magnesi-um; aryloxy magnesium, preferably C6-C30 aryloxy magnesiums, such as phenoxy magnesium and dimethylphenoxy magnesium: and magnesium salts of carboxylic acids such as magnesium laurate and magnesium stearate. These magnesium compounds may be in the form of complexes with other metals or mixtures with other metal compounds.
Mixtures of two or more of these magnesium compounds may also be used.
Among the foregoing, preferred magnesium compounds are magnesium halides, alkoxy magnesium halides, aryloxy magnesium halides, alkoxy magnesiums and aryloxy magnesiums of the formula MgX2, Mg(OR5)X and Mg(OR5)2 (wherein X is halogen, and R is a hydrocarbon group such as an alkyl group or an aryl group optionally having a substituent such as a lower alkyl group Examples of more preferred magnesium compounds include halogen-containing magnesium compounds such as magnesium chloride, alkoxy magnesium chlorides, particularly Cl-C10 alkoxy magnesium chlorides, and aryloxy magnesium chlorides, especially C6-C20 aryloxy magnesium chlorides.
Magnesium chloride is especially preferred.
Suitable liquid magnesium compounds are solu-tions of these magnesium compounds in hydrocarbon solvents, or electron donors or a mixture of both.
Examples of the hydrocarbon solvents used for this purpose are aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, tetradecane and kerosene; alicyclic hydrocarbons such as cyclo-pentane, methyl cyclopentane, cyclohexane, methyl cyclo-hexane, cyclooctane and cyclohexene; aromatic hydro-5~
_ g _ carbons such as benzene, toluene, xylene, ethylbenzene~
cumene and cymene; and halogenated hydrocarbons such as dichluroethane, dichloropropane, trichloroethylene, carbon tetrachloride and chlorobenæene.
Such a solution of a magnesium compound in a hydrocarbon solvent can be formed, for example, by simply mixing the two (using, for example, Mg~OR3)2 in which R3 is a C6-C2~ hydrocarbon); mixing the two and heating the mixture; or using an electron donor soluble in the magnesi-um compound, such as an alcohol, an aldehyde, an amine, a carboxylic acid or mixtures of these, or a mixture thereof with another electron donor, and as required, heating the mixture.
As one of the above embodiment, the case of dissolving a halogen-containing magnesium compound in a hydrocarbon solvent using an alcohol will be described.
The alcohol may be used in an amount of at least 1 mole, peferably about 1 to about 20 moles, specially preferably about 1.5 to about 12 moles, per mole of the halogen-containing magnesium compound, although its amount mayvary depending upon the type and amount of the hydro-carbon sovlent, the type of the magnesium compound, etc.
The alcohol can be used in the above-exemplified amounts when an aliphatic hydrocarbon and/or an alicyclic hydro-carbon is used. If an alcohol having at least 6 carbonatoms is used, the halogen-containing magnesium compound can be dissolved by using the alcohol in an amount of at least 1 mole, preferably at least 1.5 moles, per mole of the halogen-containing magnesium compound. Since a catalyst component having high activity can be obtained by using a lesser total amount of the alcohol, this embodiment is pre~erred. If only an alcohol having 5 or less carbon atoms is used, it must be used in a total amount of at least about 15 moles per mole of the halogen-containing magnesium compound, and the activity of theresulting catalyst is lower than that obtained in the former embodiment~ Accordingly, the use of the former embodiment is preferred. On the other hand, when an aromatic hydrocarbon is used as the hydrocarbon solvent, the halogen-containing magnesium compound can be dis-solved by using it in an amount of, for example, about 1mole to about 20 moles, preferably about 1.5 to about 12 moles, irrespective of the type of the alcohol used.
Contactiny of the halogen-containing magnesium compound with the alcohol is carried out preferably in a hydrocarbon medium. This contacting can be carried out at room temperature or a higher temperature. Tempera-tures of at least about 65C, preferably about 80 to about 300C, more preferably about 100 to about 200C, and periods of about 15 minutes to about 5 hours, preferably about 30 minutes to about 2 hours, may be cited as ex-amples although they may be properly selected according to the types of the magnesium compound and the catalyst.
Examples of the electron donors used to form the liquid magnesium compounds include alcohols having at least 6 r preferably 6 to 20, carbon atoms, such as 2-methylpentanol, 2 ethylbutanol, n-heptanol, n-octanol,

2 ethylhexanol, decanol, dodecanol, tetradecyl alcohol, undecanol, oleyl alcohol and stearyl alcohol; alicyclic alcohols such as cyclohexanol and methylcyclohexanol;
aromatic alcohols such as benzyl alcohol, methylbenzyl alcohol, isopropyl benzyl alcohol, alpha-methylbenzyl alcohol and alpha~ alpha-dimethyl benzyl alcohal; and alkoxy-containing aliphatic alcohols such as n-butyl Cellosolve and l-butoxy-2-propanol. Examples oE other alcohols include alcohols having 5 or less carbon atoms SUcil as methanol, ethanol, propanol, butanol, ethylene glycol and methyl carbitol.
Examples of the carboxylic acids used to form the liquid magnesium compound are organic carboxylic acids having at least 7 carbon atoms, preferably 7 to 20 carbon atoms, such as caprylic acid, 2-ethylhexanoic 5~

acid, undecylenic acid, und~canoic acid, nonylic acid and octanoic acid Examples of the aldehydes used to form the liquid magnesium compound are aldehydes having at leat 7 carbon atoms, preferably 7 to 18 carbon atoms, such as capr~lic aldehyde, 2-ethylhexyl aldehyde, caprylaldehyde and undecylic aldehyde. Examples of the amines used to form the liquid magnesium compound are amines having at least ~ carbon atoms, preferably 6 to lS carbon atoms~
such as heptylamine, octylamne, nonylamine, decylamine, laurylaminev undecylamine and ~-ethylhexylamine.
The magnesium compound solution may be a solu-tion in an electron donor. Examples of preferred electron donors used for this purpose include alcohols, amines, aldehydes and carboxylic acids, above all the alcohols. Examples of such electron donors may be the same as exemplified above with regard to the case of dissolving magnesium compounds in hydrocabon solvents.
Other examples of electron donors which can be used to form the liquid magnesium compounds are phenols, ketones, esters, ethers, amides, acid anhydrides, acid halides, nitriles and isocyanates.
The quantities oE the compounds or the dissolv-ing temperarture used to produce these solutions are substantially the same as those used in dissolving the magnesium compound in a hydrocarbon solvent using an electron donor as described above.
Since high temperatures must generally be maintained, the use of a solution of the magnesium com-pound in a hydrocarbon makes it easier to prepare acatalyst of high performance. Another examples of the magnesium compound in the liquid state is a melt of the magnesium compound.
Typical examples include melts of complex of magnesium halides with electron donors such as those exemplified hereinabove. Preferred are melts of magnesium f~5 halide/alcohol complexes represented by MgX2.nRlOH (Rl is a hydrocarbon group, and n is a positive number).
In the present invention, the hydrocarbon solvent-insoluble magnesium/aluminum solid complex ~A 1) is derived from the liquicl magnesium compound which can be formed as described above and an organoaluminum com-pound. The solid complex ~A-l) contains 0.01 to 0.5 yram~equivalenti preferably 0.03 to 0.3 gram-equivalent, more preferably 0~05 to 0.2 gram-ec~uivalent, per Mg atom, of a hydrocarbon group R2 having reducibility, and n.s to 15 parts by weightO preferably 1 to 10 parts by weight;
more preferably 2 to 6 parts by weight, of an organic group ORl ~wherein Rl represents a hydrocarbon group~
having no reduciability.
lS The solid complex tA-l) contains Mg and Al attributed to the liquid magnesium compound and the organoaluminum compound from which it is derived. The Al~Mg atomic ratio in the solid complex (A-l) is prefer-ably from 0.05 to 1, more preferably from 0.08 to 0.5, especially preferably from 0.12 to 0.3. Usually, the solid complex (A-l) contains halogen attributed to the liquid maynesium compound and the organoaluminum compound from which it is derived and a halogenating agent to be described below~ The halogen/Mg atomic ratio in the solid complex ~A-l) is preferably from 1 to 3, more preferably from 1.5 to 2.5. The solid complex (A-l) may further contain an electron donor or another compound attributed to the liquid magnesium compound and the organoaluminum compound from which it is derived.
The hydrocarbon solvent-insoluble magnesium/
aluminum solid complex (A-l) can be formed by contacting the liquid magnesium compound anc] the organoaluminum compound. The resultiny complex ~A-l~ contains the hydrocarbon group R2 having reducibility and the organic group OR (wherein R is a hydrocarbon group and may be the same as, or different from, R2 having no reduciability in the amounts which satisfy the requirement Examples of the hydrocarbon group R2 having reducibility are linear or branched alkyl groups having 1 s to 10 carbon atoms such as methyl, ethyl, propyl, butyl, hexyl and octyl, aryl groups having 6 to 10 carbon atoms such as phenyl and benzyl and unsaturated cyclic groups having 5 to 10 carbon atoms such as cyclopentadienyl group. Preferably, Rl is an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 2 to 8 carbon atoms. Alkyl groups having 2 to 4 carbon atoms are especially preferred.
Examples of Rl in the organic group ORl having no reducibility include linear or branched alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl t propyl, butyl, hexyl, octyl, lauryl and stearyl, alkenyl ~roups having 6 to 20 carbon atoms such as hexenyl~
octenyl, undecenyl and octadecenyl, aryl groups having 8 to 20 carbon atoms such as phenyl and benzyl, and un-saturated alkapolyenyl groups having 5 to 10 carbon atomssuch as cyclopentadienyl. Of these, alkyl groups having 2 to 20 carbon atoms and aryl groups having 6 to 10 carbon atoms are preferred. More preferably, Rl is an alkyl group having 4 to 18 carbon atoms. Branched alkyl groups having 6 to 12 carbon atoms are especially prefer-red.
The solid complex (A-l) can be formed by contact-ing the li~uid magnesium compound with the organoaluminum compound in various embodiments. For example, it can be obtained by reactiny A solution containing the above-exemplified MgX2 and the alcohol, preferably further containing a hydrocarbon, with an alkyl aluminum com-pound, or by reacting a solution containing the above-exemplified Mg~OR5)X or Mg(ORS)2 and the alcohol, prefer-ably further containing a hydrocarbon, or a hydrocarbonsolution of Mg~ORS)2 with an alkyl aluminum halide.

Examples of the alkyl aluminum compound include trialkyl aluminums such as triethyl aluminum and tributyl aluminum; trialkenyl aluminums such as triisoprenyl aluminum; dialkyl aluminum alkoxides such as diethyl aluminum ethoxide and dibutyl aluminum butoxide; alkyl aluminum sesquialkoxides such as ethyl aluminum sesqui-ethoxide and butyl aluminum sesquibutoxide; partially alkoxylated alkyl aluminums having an average composition ; represented by R3 5Al~OR4)o 5 wherein R3 and R4 re-presents represents a hydrocarbon group); dialkyl alumi-num halides such as diethyl aluminum chloride, dibutyl aluminum chloride and diethyl aluminum bromide; alkyl aluminum sesquihalides such as ethyl aluminum sesqui-chloride, butyl aluminum sesquichloride and ethyl alumi-num sesquibromide; alkyl aluminum dihalides such as ethylaluminum dichloride, propyl aluminum dichloride and butyl aluminum dibromide; dialkyl aluminum hydrides such as diethyl aluminum hydride and dibutyl aluminum hydride;
alkyl aluminum dihydrides such as ethyl aluminum di-hydride and propyl aluminum dihydride; and partiallyalkoxylated and halogenated alkyl aluminums such as ethyl aluminum ethoxy chloride, butyl aluminum butoxy chloride and ethyl aluminum ethoxy bromide.
The alkyl aluminum halide may be selected from the above-exemplified halogen-containing alkyl aluminum compounds.
Contacting of the liquid magnesium compound with the organoaluminum compound may be effected in one step or multiple steps. ~or example, the multistep contactiny may be carried out by causing the alkyl alumi-num compound with the liquid magnesium compound to form a solid magnesium compound and contactiny the resulting solid magnesium compound with the same or different alkyl aluminum compound as or from that used in the first step.
Usually, the multistep contactiny permits easier adjust-ment of the particle diameter o~ the magnesium compound, .

the amount of the organic groups, etc. and i5 easier to give a catalyst of high performance.
Desirably, the composition of the solid magnesium-aluminum complex is finally adjusted within the aforesaid range. For this purpose, it is preferred to select the amount of the alkyl aluminum in the above contacting properly. For example, the method of contact-ing the magnesium compound with the alkyl aluminum com-pound in two steps will be described. When a solution of the magnesium compound in the alcohol is used as the liquid magnesium compound, it is preferred to use the alkyl aluminum compound in such a proportion that after first-step contacting, there are at least 0.5 equivalent of bonds between the alkyl groups and aluminum atoms in the alkyl aluminum compound per equivalent of the hy-droxyl group of the alcohol. If the amount of the alkyl aluminum compound is too large, the shape of the result-ing particles is worsened and a granular catalyst some-times cannot be obtained. For this reason, it is usually preferred to use the alkyl aluminum compound in such a proportion that the amount of bonds between alkyl groups and aluminum atoms is 0.5 to 10 equivalents, preferably 0.7 to 5 equivalents, more preferably 0.9 to 3 equiva-lents, especially preferably 1.0 to 2 equivalents, per equivalent of the hydroxyl group of the alcohol.
The use of a trialkyl aluminum as the alkyl aluminum compound at this time is preerred because it permits easy preparation of a catalyst haviny a good shape. Other preferred organoaluminum compounds indlude dialkyl aluminum halidesr dialkyl aluminum hyclrides and dialkyl aluminum alkoxides.
In contacting the liquid magnesium compound with the alkyl aluminum compound, the concentration of the magnesium compound in the liquid product is prefer-ably about 0.005 to 2 moles/liter, especially about 0.05to 1 mole/liter.

~ recipitation of the magnesium compound occurs as a result of the reaction of the alkyl aluminum com-pound with the alcohol to form an insoluble magnesium compound. When the precipitation of the magnesium com-pound i5 effected abruptly, it is sometimes difficult toobtain particles having an excellent shape, a moderate particle diameter and a narrow particle size distri-bution, and the resulting particles cannot be a suitable catalyst carrier for slurry polymerization. For this reason~ it is preferred to carry out the above contact-ing under mild conditions and to precipitate a solid magnesium compound, and it is desirable to consider the contacting temperature, the amount of the alkyl aluminum compound added during the solid precipitation, the speed of adding it, the concentrations of the individual in-gredients, etc.
Preferably, the sontacting of the liquid magnesi-um compound with the organoaluminum compound is carried out at a temperature of, for example, -50 to 100C, ~o preferably -30 to 50C, and thereafter the reaction is carried out at 0 to 200C, preferably 40 to 150C. As already stated hereinabove, it is preferred to employ temperatures of 0 to 250C, especially 20 to 130C, when the resulting solid magnesium compound is further reacted with the alkyl aluminum compound under contacting.
In any case, the contacting and reacting con-ditions may be properly selected so as to meet the con-ditions specified by the requirement ~ii) of the present invention. At the seam time, it is preferred to select the contacting and reacting conditions such that the resulting complex has a particle diameter of at least 1 micrometer, especially 5 to 100 micrometers and a parti-cle size distribution, in terms of a geometric standard deviation~ of 1.0 to 2.0 and is in the form of granules.
AEter forming the solid magnesium compound, at least one organometallic compound of metals of Groups I

to III of the periodic table excluding aluminum, such as an alkyl lithium, an alkyl magnesium halide or a dialkyl magnesium, may be used instead of the alkylaluminum compound as a compound to be contacted with the solid magnesium compound in order to produce a magnesium alumi-num complex.
Another method of producing the magnesium/
aluminum solid complex (A-l) i5 to use a halogenating agent, such a~ chlorine, hydrogen chloride, silicon tetrachloride or halogenated hydrocarbons, in any desired step where the alkyl aluminum compound is used. Or the halogenating agent may be used before or after using the alkyl aluminum compound. These methods are also useful as a substitute for the method involving the use of ~he lS alkyl aluminum halide.
The use of the halogenating agent before using the alkyl aluminum compound is useful as means for form-ing a solid magnesium compound containing the group R10 or a group capable of forming the group R10 group from the liquid magnesium compound. By reacting such a solid magnesium compound with an alkyl aluminum compound, the desired magnesium/aluminum solid complex (A-l) can be produced. For example, the solid magnesium compound may be produced by reacting a solution containing the afore-said MgX2, Mg(OR )X or My(OR )2 and alcohol prefer-ably further containing a hydrocarbon, with the halogenat-ing agent, or by reacting a hydrocarbon solution of Mg(OR)2 with the halogenating agent. This solid magnesi-um compound is represented by the empirical formula MgX2 Q(ORS)~.nR60H wherein 0<~<2, n~O, R6 i5 a hydro-carbon), and sometimes contains further another compound.
In this method, the halogenating agent is used in such proportions that the amount of halogen is about 1 to 1000 equivalents per magnesium atom of the magnesium compound.
~nd the reaction of the solid magr.esium compound and the alkyl aluminum compound can be carried out in accordance with the aforesaid method of the second step in the multiple-step preparation.
Still another method of obtaining the solid mag-nesium compound is to cool and solidify MgX2 Q~OR )Q.R6OH
s in the molten state or as a dispersion in a hydrocarbon medium.
In any of the above methods, it is preferred to select precipitating conditions such that the resulting solid magnesium compound has a particle diameter of at least 1 micrometer, especially 5 to 100 micrometers and a particle size distribution, in terms of a geometrical standard deviation, of 1.0 to 2.0, and is spherical or granular.
The titanium catalyst component (A) used in the process of this invention can be obtained as a reaction product of the hydrocarbon-insoluble magnesium/aluminum solid complex tA-l) derived as shown above from the liquid magnesium compound and the organoaluminum compound [the complex (A-l~ contains 0~01 to 0.5 g equivalent, per Mg atom, of the hydrocarbon group R2 having reducing .~ ability and 0.5 to 15 parts by weight, per part by weight of Mg, of the organic group ORl having no reducibility]
with the tetravalent titanium compound (A-2). The solid complex (A-l) and the titanium compound (A-2) are reacted such that the Ti/g atomic ratio is in the range of from OoOl to 0.6, preferably from 0.04 to 0.3 lrequirement i.ii) ] .
In the present invention, the solid complex ~-1) and the titanium compound (A-2) are reacted under the conditions which satisfy the requirement (iii). The resulting titanium catalyst component (A) should meet the requirement that it contains 10 to 100 %, preferably 40 to 100%, based on the entire Ti in the component, of Ti having a lower valency state than a valence of 4 [require-ment ~i)].
If the proportion of the tetravalent titanium compound (A-2) is increased beyond the speci~ied limit of the Ti/Mg atomic ratio in requirement (iii), the amount of that portion of the ti~anium compoun~ which is not effectively used. Moreover, when the titanium compound is a halogen-containing titanium compound, the increase of the tetravalent titanium compound (A-2) undesirably decreases the amount o~ the ORl group in the resulting titanium catalyst component (A) and reduces the perEorm-ance of the catalyst. Furthermore, when the titanium compound is a tetraalkoxy titanium or a teraaryloxy titanium, the increase of the tetravalent titanium com-pound (A-2) undesirably results in dissolution of part or the whole of the solid complex (A-l) in the hydrocarbon solvent.
Preferably, the tetravalent titanium compound (A-2) used in the preparation of the solid titanium catalyst component in the present invention is a tetra-valent titanium compound represented by the formula Ti(OR)gX4 g wherein R is a hydrocarbon group, X is halogen and O<g~4. Examples of such a titanium compound include titanium tetrahalides such as TiC14, TiBr4 and TiI4; alkoxy titanium trihalides such as

3 13, Ti(OC2H5)C13, Ti(o n-C4H )Cl Ti(OC2H5)Br3 and Ti(o iso-C~Hg)Br3; alkoxy titanium dihalides such as Ti(OCH3)2C12, Ti(OC2H5)2C12, 4H9)2Cl2 and Ti(OC2H5~2Br2; trialkoxy titanium monohalides such as Ti(OCFl3)3Cl, Ti(OC2H5)3Cl, Ti~O n-C~Hg)3 and Ti~OC2H5)3Br; and tetraalkoxy titaniums such as Ti(OCEl3)~ Ti(OC2H5)~ and Ti(O n-C~Hg)~.
Among these, the titanium tetrahalides and alkoxy titani-um trihalides are preferred. The use oE alkoxytitanium trihalides is especially preferred.
The contacting reaction of the magnesium/
aluminum solid complex (~-1) with the titanium compound is carried out preferably in a hydrocarbon medium. It is advisable to select such conditions in the contacting with the titanium compound, the weight ratio of the R70 group/Mg (R is a hydrocarbon group) in the ~inal solid titanium catalyst component (A) is in the range o~ from 0.5 to 15, preferably from 1 to 10, especially pre~erably from 2 to 6. The R70 group is derived from ~he ORl yroup in the magnesium-aluminum solid complex ~A-l) and the tianium compound. If the amount o~ the R70 group is smaller than the above specified limit, slurry polymer-izability in the copolymerization of ethylene is poor, and the resulting copolymer does not have sufficiently narrow composition distribution. ~P the amount of the R70 group is larger than the above-specified limit, the activity of the resulting catalyst tends to be decreased.
The amount of the R70 group in the solid titanium catalyst component (~) is adjusted within the aforesaid range by adjusting the type and amount of the titanium compound, the contacting temperature, etc. The contacting temperature of the titanium compound is, for example, about O to 200C, preferably about 20 to 100C.
In the present invention, the solid complex ~A-l) may be formed in the presence of a porous inorganic and/or organic compound. By this procedure, the solid complex (A-l) may be deposited on the surface of such a compound. It is possible at this time to pre-contact the porous compound with the liquid magnesium compound and contact it with a liquid titanium compound while holding the liquid magnesium compound therein. Examples of such porous compounds are silica, alumina, magnesia and poly-olefins and products of treatment of these compounds with a haloyen-containing compound.
One example of the titanium catalyst component so obtained may be represented by the empirical formula MgrAlsTi~(OR7)uXlv wherein r, s, t, u and v are more than 0, and X is halogen, and may contain another compound such as a silicon compound. In the titanium catalyst component, the Ti/Mg atomic ratio is, for example, from 0.01 to 0.5, preferably from 0.02 to 0.2; the Al/Mg atomic ratio is, for example, from 0.05 to 1, preferably from 0.08 to 0.5, more preferably from 0.12 to 0.3; the Xl/Mg atomic ratio is from 1~5 to 3, preferably from 2 to 2.5; the OR7/Mg weight ratio is, for example, from 0.S to 15, preferably from 1 to 10, especially preferably from 2 to 6; and its specific surface area is, for ex-ample, 50 to 1000, preferably 150 to 500 m2/g. 10 to 100 % of all Ti atoms are Ti atoms having a lower valency state than a valence of 4. Preferably, the proportion of Ti3~ is 40 to 100 %, especially 60 to 100 %.
The arithmetic mean diameter of the titanium catalyst component ~A) is preferably 5 to 100 microme-ters, and its particle size distribution, in terms of its geometrical standard deviation in accordance with the measuring method ~o be described below, is 1~0 to 2.0, preferably 1.0 to 1.5.
In the present invention, ethylene can be copolymerized with an alpha-olefin having 3 to 10 carbon a~oms, preferably 4 to 10 carbon atoms, in the presence of a catalyst composed of the titanium catalyst component (A) and the organoaluminum compound catalyst component (B) as in a conventional process except that the titanium catalyst component ~A) is obtained as described above and meets the parametric combination of the requirements (i), ~ii) and (iii) of the present invention.
The organoaluminum compound catalyst component (B) may be properly selected from the alkyl aluminum compounds exemplified above for use in the preparation of the titanium catalyst component.
Of these, trialkyl aluminums, alkyl aluminum halides, or mixtures of these are preEerred. The dialkyl aluminum halides are especially preferred~
Examples of the alpha-olefin having 3 to 10 carbon atoms include propylene, l-butene, l-pentene, l-hexene, 4-methyl l-pentene, 3-methyl-1-pentene, l-octene and l-decene.
In the process of this invention, the copolymer-ization of ethylene with at least one alpha-olefin having 3 to 10 carbon atoms may be carried out in the liquid or vapor phase in the presence or absence of an inert polymer-ization solvent. Examples of the inert polymerization solvent whieh ean be used in the polymerization include aliphatic hydrocarbons such as propane, butane, pentane, hexarlei octane, decane and kerosene; alicyclic hydro-carbons such as eyclopentane, methyleyclopentane, eyelo-hexane and methyleyclohexane; and aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene. When the ethylene copolymer of this invention is to be pro-duced by employing the slurry polymerization methodl it is preferred to use a~ aliphatic hydrocarbon solvent.
The amounts of the catalyst eomponents ean be properly varied and changed. For example, per liter of the volume of the reaction zone, the titanium catalyst component (A) is used in an amount of preferably about 0~0005 to about 1 millimoles, more preferably about 0~001 to about 0.5 millimoles, ealculated as }itanium atom; an~
the organoaluminum eompound catalyst component (B) is used in such an amount that the aluminum/titanium atomie ratio is, for example, from about 1 to about 2000, prefer-ably from about 5 to about 100. The polymerizationtemperature may, for example, be about 20 to about 150C.
When the low-density ethylene copolymer in accordance with this invention is to be produced by slurry polymeri-zation or vapor~phase polymerizationl the polymerization is preferably carried out at a temperature of 50 to 120C. The polymerization pressure is, for example, from atmospheric pressure to about 100 kg/cm2/cm2-G, especially about 2 to about 50 kg/cm2-G.
The copolymerization may be performed in the presence of hydrogen for controlling the molecular weight of the copolymer.

The polymerization may be carried out batchwise or continuously, or in two or more steps having different conditions.
The ethylene copolymer in accordance with this invention having a density of 0.900 to 0.945 g/cm3 are obtained usually by copolymerizing ethylene with the alpha-olefin so that the ethylene content of the co-polymer becomes 85 to 99~5 % although this differs depend~
ing upon the type of the alpha-olefin.
The following Examples and Comparative Example illustrate the process of the invention more specifically.
In the following examples, the compositions, particle diameters, etc. of the catalyst components were measured by the following methods.
15 (1) Analysis of the compositions of the catalyst components (i~ Contents of magnesium, titanium, aluminum and halogen Analyzed by fluoroscent X-ray analysis.
(ii) Content of the alkoxy group The catalyst is dissolved in acetone containing a small amount of hydrochloric acid to hydrolyze the alkoxy group to an alcohol, and the amount of the alcohol in the solution is measured by gas chromatography.
(iii) The proportion of Ti having a lower valency state in the entire Ti supported on the catalyst In an atmosphere of nitrogen, the catalyst was dissolved in a lN aqueous solution of sulfuric acid, and the proportiorls of tetravalent Ti and trivalent Ti is measured by polarography (by this method, trivalent Ti and divalent Ti cannot be distinyuished from each other).
liv) Content of the hydrocarbon group R2 having reducibility in the solid complex (A-l) A flask having an inner capacity of about 1200 3~

-- 2~ --ml and equipped with a stirring device is thoroughly purged with dry nitrogen. Then, about 0.5 g of the complex (A-l) is precisely weighed and added to the flask. Subsequently, about 25 ml of water is gradually added dro~ise with stirring. This operation is carried out while avoiding leakage of the generated R2-H outside.
Twenty minutes after the end of the addition, the gaseous phase and the aqueous phase are wlthdrawn from the flask by a microsyringe, and the concentration of the generated R2-El is measured by gas chromatoyraphy.
The amount of the generated R2-H is calculated from this concentration, the volume of the gaseous phase and the volume of the aqueous phaset and from this amount, the amount of R2 contained in the complex ~A-l) is calculated.
(2) Average particle diameter of the catalyst The catalyst is photographed through an optical microscope~ On the basis of the photograph, the particle diameters of about 100 arbitrarily selected catalyst particles are measured. The arithmetic mean of the mesured values is calculated and defined as the average particle diameter.
(3) Geometrical standard deviation of the catalyst Ethylene and 4-methylpentene-1 are copolymeriz-ed by the following method (ii) using a sample catalyst.The geometrical standard deviation of the resulting polymer particles is defined as the yeometrical standard deviation of the catalyst.
(i) Method of measuring the geometrical standard deviation of the polymer particles The polymer particles are sieved with sieves having mes~, sizes of ~4 microns, 105 microns, 177 microns, 250 microns, 350 microns and 840 microns, and the weight of the polymer particles left on the individual sieves are measured.
Based on the results, the particle diameters and cumulative weiyht proportions are plotted on the abscissa and the ~,.2 ~?~L~

ordinate respectively on logarithmic probability paper to prepare a straight line or curve. By utilizing the prepared line or curve, the particle diameter ~D50) correspond to 50 % by weight and the smaller particle diameter ~D16) corresponding to 16 % by weight are determined~ and the value of D50/D16 is defined as the geometrical standard deviation.
(ii) Method of polymeri2ation PuriPied hexane ~850 ml) is charged into a 2-liter autoclave, and the autoclave is purged with ethylene at room temperature. At 60 to 65C, 1.2S
millimoles of diethyl aluminum chloride, 0.025 millimoles of the solid titanium catalyst component calculated as titanium atom, and 150 ml of 4-methylpentene-1 are added.
The catalyst charge opening is closed and the autoclave is sealed. The autoclave is pressurized with hydrogen to 1.2 kg/cm2G, and the total pressure is raised to 4 kg/cm2G with ethylene. The polymerization is carried out at 70C. When the inside temperature of the autoclave is lowered to 55C, the polymer suspension after the polymerization is taken out, quickly filtered on a filter.
The polymer powder is obtained and dried.
The polymerization time is set so that the i amount of the polymer powder yielded becomes about 150 to 2Q0 g.

lPreparation of the titanium catalyst (A)]
Commercial anhydrous magnesium chloride ~4.8 g), 23.1 ml of 2-ethylhexyl alcohol and 200 ml of decane were reacted at 140C for 3 hours to obtain a uniform solution containing magnesium chloride. While the solu-tion was stirred, a mixed solution o~ 7.1 ml of triethyl aluminum and 45 ml of decane at 20C was added drowpwise over the course of 30 minutes~ Thereafter, the mixture was heated to 80C over the course of 2.5 hours, and re-acted at 80C for 1 hour. AEter the reaction, the ~ 26 -reaction slurry was left to stand. The supernatan~ was removed, and 200 ml of decane and 6.3 ml ~50 millimoles) of diethyl aluminum chloride were added to the remaining slurry containing the solid portion formed by the above reaction~ The mixture was reacted at 80C for 1 hour.
The solid portion was then separated by filtration and washed once with 100 ml of decane to synthesize a solid component (A-l) having a reducible organic group. The composition of the solid component ~A-l) is shown in Table 1.
The solid component was suspended in 200 ml of decane, and ~.0 millimoles of 2-ethylhexoxy titanium trichloride ~Ti/Mg atomic ratio=0.08) was added, and they were reacted at 80C for 1 hour. The reaction mixture was washed with decane to prepare a solid titanium catalyst component.
A portion of the slurry was taken. Decane was removed from it, and replaced by hexane. The slurry was then dried. The composition of the dried catalyst was examined. The composition of the solid titanium catalyst component (A) is shown in Table 2.
[Polymerization]
A 2-liter autoclave was charged with 850 ml of purified hexane, and purged with ethylene at room tempera-ture. The temperature was raised, and at 60 to 65C,1.25 millimoles of diethyl aluminum chloride, 0~025 millimole, calculated as titanium atom, of the solid titanium catalyst component, and 150 ml of 4-methyl-pentene-l were added. The catalyst charge opening was closed ancl the autoclave was sealed. The autoclave was pressurized with hydrogen, and the total pressure was raised further to 4 kg/cm2G with ethylene. The polymeri-zation was carried out at 70C for 2 hours~ After the polymerization, the polymer suspension was taken out when the insi~e temperature of the autocalve was lowered to 55C, and quickly filtered on a filter to separate it into a polymer powder and a hexane-soluble portion. The hexane-soluble portion was concentrated, and the amount of the solvent-soluble polymer formed was measured. The results of the polymerization are shown in Table 3~ The particle size distribution of the polymer powder was as 5 follows:
>840 microns 0 >350 microns 0.4 >250 microns 94.0 >177 microns 5~4 >105 microns 0.2 >44 microns 0 44 microns> 0 Ethylene and 4-methylpentene-1 were copolymeriz-ed in the same way as in Example 1 except that the follow-ing organometallic compounds in the amounts indicated were used instead of 6.3 ml (50 millimoles) of diethyl aluminum chloride in the synthesis of the solid component (A-l). The results are shown in Table 3.
Example 2 Etl 5AlC11 5 50 Example 3 n-Bu3A1 65 Example 4 iso-Bu3A1 70 Example 5 n-~ex3A1 70 Example 6 EtMgBu 70 Commercial anhydrous magnesium chloride (4.8g), 23.1 ml of 2-ethylhexyl alcohol and 200 ml of decane were reacted at 140C for 3 hours to give a uniform solution containing magnesium chloride. A mixed solution of 7.1 ml of triethyl aluminum and 45 ml of decane at 20C was added dropwise to the solution with stirring over the course of 30 minutes. The temperature was then raised to 80C over the course of 2.5 hours and reacted at 80C
for 1 hour. After the reaction, the reaction slurry was left to stand and the supernatant was removed. Decane ~200 ml) and 8.9 ml of triethyl aluminum were added to the remaining slurry containing the solid portion formed by the above reaction, and the reaction was further carried out at 80C for 1 hour. The solid portion was then separated and washed once with 100 ml of decane to synthesize a solid component (A-l) having a reducible organic group. The composition of ~he solid component is shown in Table 1.
The resulting solid component was again suspend-ed in 200 ml of decane, and 0.44 ml (4.0 millimoles) of titanium tetrachloride (Ti/Mg atomic ratio=0.08) was added, and reacted at room temperature for 1 hour to give a decane suspension containing the solid titanium catalyst component. The solid titanium catalyst component (A) was analyzed, and the results are shown in Table 2.
[Polymerization]
The polymerization was carried out in the same way as in Example 1. The results are shown in Table 3.

A solid titanium catalys~ component was pre-pared by the method of ~xample 7 except that 0.44 ml of titanium tetrachoride was replaced by each of the follow-ing titanium compounds (the amount was the same as in Example 7). Using the solid titanium catalyst component~
the same polymerization as in Example 1 was carried out.
The results are shown in Table 3.
Example Titanium compound 8 Ti(OEt)4 9 Ti(O isopr)~
Ti(OBu)4 11 Ti(OEH)4 12 Ti(OBu)4 dimer 13 Ti(OBu)~ tetramer 1~ Ti(oBu)2cl2 Ti(OE~I)2C12 16 Ti(OEt)C13 17 Ti(OBu)C13 18 Ti(OE~I)C13 A solid titanium catalyst component was pre-pared by the same method as in Example 1 except that the method of preparing the liquid magnesium compound in Exarnple 1 was changed as follows. Specifically, 23.1 ml of 2-ethylhexanol was added to 200 ml of a decane suspen-sion containing 50 millimoles of ethoxy magnesium chloride, and the mixture was reacted with stirring at 140C for 3 hours to synthesize a uniform solution containing magnesium. Usiny the resulting solid titanium catalyst component, the same polymerization as in ~xample 1 was carried out.

A solid titanium catalyst component was prepared in the same way as in Example 1 using 57 ml of a decane solution containing 50 millimoles of 2-ethylhexoxy magnesi-um. Using the resulting catalyst component, the same polymerization as in Example 1 was carried out.
EX~MPLE 21 Commercial anhydrous magnesium chloride t4.8 g), 23.1 ml oE 2-ethylhexyl alcohol and 200 ml of decane were reacted at 140C for 3 hours to give a uniform solution containing magnesium chloride. Silicon tetra-chloride (8.~ ml) was added to this solution at 20C
with stirring. The mixture was heated to 50C, and reacted at this temperature for 5 hours to form a solid containing 42 ~ by weight of 2-ethylhexanol. After the reaction, the solid was separated by filtration, and suspended in 100 ml of decane. Triethyl aluminum (8.6 ml) was added, and the reaction as carried out at 80C
for 1 our. The solid portion was separated by fil-tration, and suspended in 200 ml of decane. A decane solution of titanium ethoxy trichloride was added in an amount of ~ millimoles calculated as titanium atom, and the mixture was stirred at room temperature for 1 hour to form a decane suspension of a solid titanium catalyst component. Using this catalyst component, the same polymerization as in Example 1 was carried out. The results of the polymerization are shown in Table 3.

A 2-liter high-speed stirring device (made by Tokushu Kika Kogyo) was fully purged with N2 and charged with 700 ml of purified kerosene, 10 g of commercial MyC12, 24.2 g of ethanol and 3 g of Emasol 320 (a trade name for sorbitan distearate produced by Kao-Atlas Co., Ltd.). The mixture was heated with stirring, and stirred for 30 minutes at 120C and B00 rpm. With stirring at high speed, the mixture was transferred by means of a Teflon tube having an inside diameter of 5 mm to a 2-liter glass flask (equipped with a stirrer) in which 1 liter of purified kerosene cooled to -10 C had been placed. The resulting solid was collected by filtration, and fully washed with hexane to obtain a carrier.
Ten grams of the carrier (containing 43 milli-moles of magnesium) was suspended in 100 ml of decane, and while the suspension was maintained at -10C, 87 ml of diethyl aluminum chloride diluted with decane to 1 mole/liter was added dropwise over the course of 1 our.
The mixture was heated to 80C over the course of 2 hours, and reacted at this temperature for 2 hours. The solid portion was separated, and suspended in 100 ml of decane. Titanium tetrachloride (0.43 ml; Ti/Mg atomic ratio=0.09) was added, and the reaction was carried out at 80C for 1 hour to prepare a solid titanium catalyst component. The same polymerization as in Example 1 was carried out using the resulting catalyst component. The results of the polymerization are shown in Table 3.

A 2-liter fully purged autoclave was charged with 1 liter of purified hexane, 1.25 millimoles of diethyl aluminum chloride, and then 0.025 millimole, calculated as titanium atom, of the solid titanium catalyst component prepared in Example 1. ~Iydrogen under f ~ ~Cr D ~ ~

1.0 kg/cm2 was introduced into the autoclave, and the temperature was raised to 70C. A gaseous mlxture of ethylene and butene-l with a butene-l content of 18.0 mole% was fed into the autoclave and polymerized at 5 70C under a total pressure of 3.5 kg/cm2G for 2 hours.
There was obtained 245.5 g of a polymer powder having an apparent bulk density of 0.38 g/ml, an MFR of 1.1 dg/min.
and a density of 0.926 g/ml. There was also formed 2.7 g of a hexane-soluble polymer. Accordingly, the polymeri-10 zation activity was 9,900 g-PE/mmole-Ti and the yield was 98.9 ~ by weight. The proportion of the hexane-soluble portion was 1.1 % by weightr A solid titanium catalyst component was prepared 15 by the same method as described in Example 1 of Japanese Patent Publication No. 19122/1982 (corresponding to British Patent No. 1,485,520). Specifically, 19.0 g of anhydrous magnesium chloride powder was suspended in 200 ml of kerosene, and 70 1 ml of ethanol was added. They 20 were mixed with stirring for 1 hour. Then, 70.4 ml of diethyl aluminum chloride was added dropwise over 30 minutes using a dropping funnel and mixed at 20C for hour. Then, 13.2 ml of titanium tetrachloride and 16~4 ml of triethyl aluminum were added and mixed with stirring ~5 at room temperature for 4 hours to obtain a kerosene suspension of a solid titanium catalyst component. This catalyst component had a geometrical standard deviation of 1.~.
The same polymerization as in Example 1 was 30 carried out usiny the resulting solid titanium catalyst component.
The results are shown in Tables 4 and 5.

~ solid t~tanium catalyst component was prepared 35 by the same method as described in Example 10 of Japanese Patent Publication No. 32270/1975 ~corresponding to British Patent No. 1,433,537) . Specifically, 19.0 g of anhydrous magnesium chloride was suspended in ~00 ml of kerosene, and 0.1 ml of ethanol was added with stirring.
The reaction was carried out at room temperature for l hour. Then, 73.0 ml of ethyl aluminum sesquichloride was added dropwise and mixed for 1 hour. Titanium tetra-chloride (100 ml) was added dropwise, and with stirring, the mixture was heated to 100C with stirriny, and reacted a~ this temperature Eor 3 hours. Tbe solid portion was separated by decantation, and suspended in kerosene to obtain a kerosene suspension of a solid titanium catalyst component. This catalyst component had a geometrical standard deviation of 1 6.
The same polymerization as in Example 1 was carried out.
The results are shown in Tables 4 and 5.

A l-liter glass flask was charged with 500 ml of n-decane, and the temperature was raised to 95C
while a gaseous mixture of propylene and ethylene (in a mole ratio of 60:40) was passed througn the liquid phase in the flask at a flow rate of 100 liters/hour. Then, 1.0 millimole of diethyl aluminum chloride and 0.05 millimole, calculated as titanium atom, of the solid titanium catalyst component prepared in Example 1 were added, and propylene and ethylene were copolymerized at 100C for 50 minutes. During the polymerization, the gaseous mixture of the above composition was passed through the liquid phase in the flask at a constant rate of 200 liters/hour. After the lapse oE a predetermined period of time, about 5 ml of butyl alcohol was added dropwise to stop the polymerization. The polymer solu-tiorl was added to 4 liters of methanol with stirring to precipitate the resulting polymer. The polylrler so ob-tained was dried fully. Its amount was 53.8 g, and it 3~ was a copolymer containing 63 mole ~ of propylene.
IR measurement hardly revealed chains consist-ing of 5 or more methylene radicals, and this suggests that the copolymer obtained has a narrow composition distribution.

Titanium catalyst components were prepared in accordance with the methods of Examples 1 and 2 of Japanese Laid-Open Patent Publication No. 11908/1981.
These catalyst components had the following compositions.

Comparative Example Ti/Mg atomic ratio 0.1 0.09 Al/Mg atomic ratio 0.06 0 X/Mg atomic ratio 2.5 2.4 ORl/Mg weight ratio 0.08 0.06 In addition to these components, the catalyst component contained 10.2 % (Comparative Example 3) or 11.0 ~ ~Comparative Example 4) of ethyl benzoate. O
is 2-ethylhexoxy.
The same polymerization as in Example 1 was carried out using each of these titanium catalyst com-ponents. The results are shown below ComlLæ~

g-PE/mmole-Ti 6,100 5,700 Yield ~wt. %) 81.6 74.6 Proportion of the hexane~soluble 18.4 25.5 portion ~wt. ~) MFR ~dy/min.) 1.4 1.8 Density ~g/ml) 0.932 0.933 Bulk density ~g/ml) 0.26 0.24 It is seen that the proportion of the hexane-soluble portion was very great, and the polymer obtained had a low bulk density.
COMP~RATIVE EXAMPLE 5 The procedure up to the treatment with ethyl aluminum (reaction at 80C for 1 hour) in Exa~ple 1, [Preparation of a titanium catalyst (A)] was carried out.
The resultiny slurry was filtered to separate the solid portion. The solid portion was washed once with 200 ml o~ hexane, and suspended in 100 ml of decane. Then, 100 millimoles of 2-ethylhexoxy titanium trichloride tTi/Mg atomic ratio=2) was added, and reacted at 80C for 1 hour. The reaction product was washed and otherwise worked up in the same way as in Example 1.
The resulting titanium catalyst component had the following composition t% by weight).
Ti: 2.8 Cl: 55 Mg: 17 Al: 1 ORl: 24.3 ORl/Mg weight ratio: 1.4 Al/Mg atomic ratio: 0.05 tORl: 2-ethylhexoxy group) Ethylene and 4~methylpentene-1 were copolymeri-zed in the same way as in Example 1 using the resulting titanium catalyst component. The results were as folows:-g-PE/mmole-Ti: 12,800 Yield t~): 80.7 Proportion of the hexane-soluble portion t%): 19.3 MFR tdg/min.): 5.3 Density tg/l): 0.934 Bulk density tg/ml): 0.26 It is seen that the proportion of the hexane-soluble portion was large, and the polymer had a low bulk density.

Table 1 Composition of (A-l) __ . .. _ ................................. . ~
Example Al/Mg ORl/Mg Cl/Mg R2/Mg No.(atomic ratio) (weight ratio) (atomic ratio~ tg-equivalent per Mg ato~
.. ___ .. ~ .
1 0.26 5.1 2.3 0.07 2 0.21 5.0 2.3 0.07 3 0.28 7.0 2.5 0.07

4 0.22 ~.8 2.3 0.08 0.30 6.5 2.3 0.06 6 0.27 ~.1 2.1 0.08 7 - 18 0.18 3.6 2.2 0.09 r;tt~J N ~ 1~1 r-l NN ~It~ ) N ~ N
ti~ ~ ~ ~t r-tr-l r ~ r t r t r-l r-tr~l r-t r-l r^t r-t r t r~l r-t ~ ~t ~--1 ~ ..._ ., . ~
~ ~ r,~ a,l ~t ~ 'i3 ~ r Jr-t ~3 r-t C;~ r^~rt ~ ~ r~
.~ ~ ~r r0 -- ' - ~~--~ ' ~-----'~---- _ -- _ __ O

O ~ o11'~ Ir)O OIf ~ IJ^) 11~11'~ 0 0 ~')L~ 1~ ~ u \ r~
~ ~X
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r-l g ~ L~ ~ ~ ~ ~I r~ \t I~S
- , . ~
~ ~ ~1CS~ ~ CO1~ (~) t'~l O 1~ COr,o i~ Or-~ CO 1~ 0 a~ O O
r1 ~ ~3 ~r-l r-l ~ r~ l ~ r-l O O OOr-l r-l O O O O r-l ~ r0 ~ ~r~ 0 ~1) O OO O O O O O O O O OO O O O O O ~ :~
~ .__ ~ ~
O ~ O O O O r-l O r-l ~D 1~ C~ O O
1~ 1~ 0~
~ ~ U o o~ r~l ~-a JJ ~ 1~1 r-Jr-l r-1 ~1 r~l ~ r-1r-lr~l r-l r-l r~l r-J r-l r-l r-l r~l ~1 ~
~ ~ o d~
~ OOOOOOOOOOOOOOOOOO
r~ ~ 0 O

~1 ~ .~ r-~
_ r-l r-l r-lr~r-l r~l r~ ~I r-l Table 3: Results of polymerization __ Proportion of Bulk Example q-PE Yield the hexane-soluble MFR Density density No, mmol-Ti portion (wt S) (wt %) tdg/min) (g/ml) ~g/ml) 1 8,600 94.4 5.6 1.4 O.g25 0.37 2 8,700 96.3 3.7 0.5 0.928 0.3~
3 5,600 95.0 5.0 1.7 0.931 0.34 4 6,400 96.8 3.2 1.7 0.932 0.34 10,200 ~6.4 3.6 1.0 0.930 0.35 6 6,400 95.5 4.5 0.5 0.929 0.36 7 7,000 95.4 4.6 1.3 0.932 0.3~
8 10,500 95.7 4.3 1.7 0.933 0.35 9 4,600 96.8 3.2 1.5 0.935 0.37 9,500 96.4 3.6 2.7 0.936 0.37 11 6,100 96.9 3.1 1.0 0.936 0O3~
12 8,200 95.0 5.0 2.2 0.934 0.35 13 5,800 95.1 ~.9 2.5 0.935 0.36 14 6,700 95.1 ~.9 1.~ 0.933 0.37 7,400 95.1 ~.9 2.0 0.934 0.37 16 6,600 95.6 ~.~ 1.4 0.932 0.36 17 5,800 95.2 ~.8 1.8 0.932 0.36 l8 7,800 95.1 ~.9 1.5 0.931 ~.35 19 5,700 9~.6 5.~ 0.7 0.935 0.3~
6,100 94.2 5.8 0.7 0.933 0.33 21 9,600 92.1 7.9 0.8 0.931 0.36 22 10,300 9l.0 9.0 0.7 ~.931 0.3 tb $~ 5;

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Claims (9)

What is claimed is:

1. A process for producing a copolymer comprising a major proportion of ethylene and a minor proportion of at least one alpha-olefin which comprises copolymerizing ethylene with at least one alpha-olefin having 3 to 10 carbon atoms in the presence of a catalyst composed of (A) a titanium catalyst component which is the reaction product of (A-1) a hydrocarbon solvent-insoluble magnesium/aluminum solid complex derived from a liquid magnesium compound and an organoaluminum compound, with (A-2) a tetra-valent titanium catalyst compound, and (B) an organoaluminum compound catalyst com-ponent;
wherein (i) the titanium catalyst component (A) con-tains 10 to 100 %, based on the entire Ti in the com-ponent, of Ti of a lower valency state than a valence of 4, (ii) the solid complex (A-1) contains 0.01 to 0.5 g-equivalent, per Mg atom, of a hydrocarbon group R2 having reducibility and 0.5 to 15 parts by weight, per part by weight of Mg, of an organic group OR
(where R1 represents a hydrocarbon group) having no reducibility, (iii) the titanium catalyst component (A) is a reaction product obtained by reacting the solid complex (A-1) and the tetravalet titanium compound (A-2) under such conditions that the Ti/Mg atomic ratio of (A-1) and (A-2) is from 0.01 to 0.6, and (iv) the resulting ethylene copolymer has an ethylene content of 85 to 99.5 mole % and a density of 0.900 to 0.945 g/cm3.

2. The process of claim 1 wherein the solid com-plex (A-1) has an A1/Mg atomic ratio of from 0.05 to 1, and a halogen/Mg atomic ratio of from 1 to 3.

3. The process of claim 1 wherein the titanium catalyst component (A) has a Ti/Mg atomic ratio of from 0.01 to 0.5, an A1/Mg atomic ratio of from 0.05 to 1, a halogen/Mg atomic ratio of from 1.5 to 3 and a weight ratio of the organic group OR7 (wherein R7 is a hydrocarbon group) having no reducibility to Mg of from 0.5 to 15.

4. The process of claim 1 wherein the amount of the titanium catalyst component (A) is about 0.0005 to about 1 millimoles, calculated as titanium atom, per liter of the volume of the reaction zone, and the amount of the organoaluminum compound catalyst component (B), in terms of the A1/Ti atomic ratio, of from about 1 to about 2,000.

5. The process of claim 1 wherein the copolymeriza-tion is carried out at a temperature of about 20 to about 150 °C and a pressure of atmospheric pressure to about 100 kg/cm2-G.

6. The process of claim 1 wherein the titanium catalyst component (A) is formed by reacting the solid complex (A-1) with the tetravalent titanium compound (A-2) in the presence of a hydrocarbon solvent.

7. The process of claim 1 wherein the titanium catalyst component (A) contains 40 to 100 %, based on the entire Ti in the component, of Ti of a lower valency state than a valence of 4.

8. The process of claim 1 wherein the ethylene copolymer has a density of 0.900 to 0.945 g/cm3.

9. A process for producing an ethylene copolymer having a density of 0.900 to 0.945 and containing a major proportion of ethylene and a minor proportion of at least one alpha-olefin which comprises copolymerizing ethylene with at least one alpha-olefin having 3 to 10 carbon atoms in the presence of a solid titanium catalyst, wherein the solid titanium catalyst meets all of the following conditions (a), (b) and (c):

(a) the catalyst contains magnesium atoms (Mg), aluminum atoms (Al), titanium atoms (Ti), halogen atoms (X1) and a non-reducible OR7 group (wherein R7 isahydro-carbon group) as essential components, and has a Ti/Mg atomic ratio of from 0.01 to 0.5, an A1/Mg atomic ratio of from 0.08 to 1, an X1/Mg atomic ratio of from 1.5 to 3, and an OR7/Mg weight ratio of from 0.5 to 15., (b) 10 to 100% of the titanium atoms have a lower valency state than a valence of 4, and (c) the solid titanium catalyst has an average particle diameter of 5 to 100 micrometers and a particle size distribution represented by a geometrical standard deviation of 1.0 to 2Ø