GB1582395A - Process for preparing titanium trichloride compositions suitable for use as the transition metal component of ziegler-type catalysts - Google Patents

Description

(54) PROCESS FOR PREPARING TITANIUM TRICHLORIDE COMPOSITIONS SUITABLE FOR USE AS THE TRANSITION METAL COMPONENT OF ZIEGLER-TYPE CATALYSTS (71) We MITSUBISHI PETROCHEMICAL COMPANY LIMITED., a company organized and existing under the Laws of Japan, of 5-2, Marunouchi 2-chome, Chiyoda-ku, Tokyo-to, Japan. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for producing titanium trichloride compositions suitable for use as the transition metal component of Ziegler-type catalysts. More specifically. the present invention relates to a process for producing a Ziegler-type catalyst component for the polymerization of a-olefins having high stereospecificity and polymerization activity by reducing and activating titanium tetrachloride according to a particular embodiment of the invention.

The present invention also relates to a process for producing highly stereospecific a-olefin polvmers in a high yield.

It is well known that Ziegler-type catalysts are used as catalysts for the stereospecific polymerization of ct-olefins. It is also well known that the transition metal compound titanium trichloride is one of the primary components of Ziegler-type catalysts. The titanium trichloride is combined with an organoaluminium compound, which is another primary component of a Ziegler-type catalyst, to form the catalyst.

The titanium trichloride is prepared by reducing titanium tetrachloride. Ordinarily, titanium trichloride which contains the reduction reaction products of a reducing agent and other materials is used as a titanium trichloride composition for the catalyst component.

As pne of the titanium trichloride catalyst components which have been widelv used for industrial purposes. there is known a titanium trichloride catalyst component prepared by reducing titanium tetrachloride with an organoaluminium compound or metallic aluminium. The titanium trichloride catalyst component so prepared is a titanium trichloride composition containing a certain amount of aluminium chloride (for example, substantially 1/3rd mole of aluminium chloride per mole of titanium trichloride).

In polymerizing the olefins by using a Ziegler-type catalyst containing such a titanium trichloride composition. it is naturallv required that the stereospecificity of the resulting olefin polymers should be as high as possible, and that such polymers should be produced in as high a yield as possible. Various studies have been made to develop a catalyst capable of satisfying such requirements. Most of the studies appear to be directed to an improvement in the titanium trichloride composition.

For example, U.K. Patent No. 1391()68 describes and claims a process for producing a titanium trichloride composition which comprises reducing titanium tetrachloride with an organoaluminiuln compound. treating the resulting reduced solid (viz. titanium trichloride composition) with a complexing agent and further contacting the solid so treated with titanium tetrachloride. A Ziegler-type catalyst composed of the titanium trichloride composition so obtained has a high activity and, at the same time. imparts good stereospecificitv to the resulting olefin polymer. Accordingly. it can probably be stated that the titanium trichloride composition of the above-mentioned U.K. Patent is one of the best compositions which have been hitherto proposed.

The titanium trichloride prepared by reducing titanium tetrachloride with the organoaluminium compound according to the known method is of ss-modification or form in its crystal state. It is believed that the titanium trichloride is converted into a y- or ö- titanium trichloride by further treatment of the ss-modification with the complexing agent and titanium tetrachloride. In this case, it seems to be essentital, in order to obtain a high activity that the titanium trichloride produced by the reduction should be of B-modification, and that this titanium trichloride should be converted into other crystal structures.

A process for treating a titanium trichloride composition obtained by reducing titanium tetrachloride with metallic aluminium instead of the organolaluminium compound in the same procedure described above has also been proposed (e.g., in U.K. Patent No.

1370559). In this process, the titanium trichloride produced by the reduction is of y-modification in its crystal form, and a Ziegler catalyst composed of a titanium trichloride composition resulting from the starting y-titanium trichloride is far less active than the Ziegler catalyst composed of the titanium trichloride composition resulting from the titanium trichloride (ss-modification) prepared by reduction with the organoaluminium compound.

On the other hand, U.S. Patent No. 3,032,510 discloses a process for improving the polymerization activity of a Ziegler catalyst by dry-pulverizing a titanium trichloride composition which can be ordinarily used as a catalyst component for the stereospecific polymerization of ot-olefins. However, as is fully described hereinafter. the pulverizing treatment does not always provide an improvement in activity.

The present invention provides a process for producing a titanium trichloride composition which is capable of providing a Ziegler type catalyst having a remarkably improved polvmerization activity and producing a-olefin polymers possessing high stereospecificity. According to the present invention this is achieved by subjecting titanium trichloride prepared by reducing titanium tetrachloride with one or more organoaluminium compounds to activation bv heat treatment. pulverization. treatment with a complexing agent and treatment with a halogen compound.

Therefore, in accordance with the present invention there is provided a process for producing a titanium trichloride composition suitable for use as the transition metal component of a Ziegler-type catalyst. which process comprises the steps of: (1) reducing titanium tetrachloride with at least one organoaluminium compound to produce titanium trichloride having a crystal structure: (2) heat treating the resulting titanium trichloride (of form) at a temperature within the range of from 1()0 C to '()() C inclusive. to convert the titanium trichloride from the beta to the gamma form. and subsequently pulverizing the heat-treated titanium trichloride. in the presence or absence of titanium tetrachloride. to produce a titanium trichloride composition containing titanium trichloride which is amorphous or of delta structure and containing substantially no titanium trichloride having a crystal structure: (3) treating the resulting pulverized titanium trichloride composition with an organic complexing agent: and (4) treating the resulting titanium trichloride composition with at least one inorganic halogen compound consisting of at least one halide having Lewis acidity or an interhalogen compound (hereinafter referred to as a halogen compound). or any mixture or combination thereof.

A Ziegler-type catalyst comprising the titanium trichloride composition prepared from a combination of the above-described particular steps has a higher activity than that comprising the titanium trichloride disclosed in the above-mentioned U.K. Patent No.

1391068. By the utilization of the high polymerization activity and stereospecificity of the Ziegler-type catalyst of the present invention. it is possible to produce a-olefin polymers containing a very small quantity of atactic polymer by-products without any need for the removal of the catalyst residues.

Such excellent catalytic performance. particularly high activity. can be obtained by a critical combination of the above-mentioned steps. That is. first. pulverization provides no desired effect unless the titanium trichloride composition subjected to the pulverizing step is a titanium trichloride composition containing substantially no titanium trichloride which composition has been prepared by heat treating a titanium trichloride so as to transform the [3-modification into a -modification. and the lA-titanium trichloride itself is a reduction product of titanium tetrachloride with at least one organo aluminium compound.

That is. for example. when the final treated solid obtained by the method described in U.K.

Patent No. 1.3()1.()6 subjected to a pulverization treatment. it is recognized that a Ziegler-type catalyst comprising the pulverized solid is remarkably inferior in polvmerization activity as compared with a Ziegler-type catalyst comprising the solid which has not been subjected to pulverization treatment (reference is made in this connection) to Comparative Example 9 set forth hereinafter).

Also, in the case where a reduced solid prepared by reducing titanium tetrachloride with the organoaluminium compound is subjected to a pulverization treatment without heat treating the solid, even if the pulverized solid is subsequently subjected to the complexing agent treatment, and to treatment with a halogen compound as described in U.K. Patent No. 1,391,068, the resulting solid will still have a less effective catalytic performance (reference is made in this connection to Comparative Example 10 (below)).

Further, in the process of the present invention, it is necessary that the heat treatment should be conducted prior to the pulverization process, and that the two processes should be conducted in a continuous sequence. Thus, for example, a reduction-heat treatmentcomplexing-halogen compound treatment-pulverization or reduction-heat treatmentcomplexing-pulverization-halogen compound treatment process order is unable to provide such an excellent catalytic performance as is realized by means of the process of the present invention (reference is made in this connection to Comparative Examples 4 and 5 (below)).

Furthermore, a combination of heat treatment-pulverization treatment must be carried out subsequent to the reduction process. Thus, for example, a reduction-complexing-heat treatment-pulverization-halogen compound treatment process order cannot provide really good catalytic performance (reference is made in this connection to Comparative Example 6 (below)).

In addition, although a process for producing a titanium trichloride composition of high polymerization activity by subjecting the titanium trichloride composition (t3-modification) prepared by reducing titanium tetrachloride with the organoaluminium compound to the organic complexing agent and titanium tetrachloride treatments has already been taught in the above-mentioned U.K. Patent No. 1,391,068, the complexing agent and the halogen compound treatments of the heat-treated solid (y-titanium trichloride) without the pulverization thereof in accordance with the process of the present invention does not provide excellent catalytic performance (reference is made in this connection to comparative Example X (below)).

Additionally. it is necessary in the process of the present invention that pulverization should be carried out under conditions such that a crystal structure does not substantially appear in the pulverized titanium trichloride composition (hereinafter fully described). It has been stated that a titanium trichloride composition obtained by reducing titanium tetrachloride at a low temperature with an organoaluminium compound having the formula AlRnCI3 " wherein n is a number in the range of from 1 to 3, has a crystal structure, and the titanium trichloride when heated to a temperature above 100"C is transformed into a y-titanium trichloride. The heat-treatment process of the present invention utilizes this phenomenon.

It has also been stated that, if even a titanium trichloride composition in which the crystal structure has been confirmed as undergoing a definite transition from a ss-modification to a γ-modification during the heat treatment is pulverized, the γ-crystal structure of the composition will be generally transformed into a #- form or an amorphous form. However, the phenomenon that a ss-crystal structure appears in the pulverized composition depending upon the pulverization conditions has now been confirmed by us through the results of X-ray diffraction analysis). This phenomenon is believed to have been unknown hitherto.

It is considered that the invention described in the above-mentioned U.K. Patent No.

1.391,068 aims at achieving an improvement in performance by subjecting the í3-titanium trichloride composition obtained from the reduction of titanium tetrachloride with the organoaluminium compound to the complexing agent and titanium tetrachloride treatments because the [3-titanium trichloride composition is unfavourable in terms of catalytic activity and the stereospecificitv of the resulting polymer.

However, even if the pulverized composition in which the ss-crystal structure has appeared as stated above is subjected to the treatments (complexing agent and titanium tetrachloride treatments) of the known process, only a remarkably low catalytic activity is afforded (reference is made in this connection to Comparative Example 11 (below)).

Concrete pulverization conditions under which no substantial appearance of the [3-crystal structure occurs are determined in relation to reduction conditions and heat treatment conditions. It is also possible to suppress the appearance of the l3-clystal structure by pulverizing the heat-treated titanium trichloride composition in the presence of titanium tetrachloride (full illustrations are given below).

The present invention is now described in further detail.

1. Reclitcnoj of titC il(iii tetiyichIoi'iIe The reduction of titanium tetrachloiide with an organoaluminium compound may be carried out by conventional methods.

Organoaluminium compounds suitable for use as a reducing agent are those having the formula AlRnCl3-n, wherein n is greater than 0, but not greater than 3, preferably not greater than 2, i.e., 0 < n #3, or preferably 0 < ns2, and R represents a residue of hydrocarbons having from 1 to 10 carbon atoms. Examples of such brganoaluminium compounds are: triethylaluminium (TEA), diethylaluminium chloride (DEAC), diisopropylaluminium chloride, diphenylaluminium chloride, ethylaluminium sesquichloride (EASC), and ethylaluminium dichloride (EADC). These compounds may be used alone or as mixtures.

The molar ratio of organoaluminium compound to titanium tetrachloride may be suitably determined depending upon the type of organoaluminium compound used. Specifically. for example, for DEAC, an approximately equimolar ratio of DEAC to titanium tetrachloride is preferred; for EASC, any molar ratio provides approximately equal results provided that the atomic ratio of Al to Ti exceeds zero but is less than 3:1 and for EADC, any molar ratio of EADC to titanium tetrachloride is possible although the preferred molar ratio of EADC/TiC14 is in the range of from substantially 1:1 to 3:1. Even molar ratios other than these preferred ratios can provide satisfactory results if the treatment conditions of the subsequent processes are suitably adjusted.

The reduction temperature is ordinarily in the range of from -3() C to 30 C, and most preferably from -5 C to +5 C.

The reduction time may be optionally varied provided it is sufficient to ensure the attainment of the required reduction. Preferably, the organoaluminium compound is dropped into the titanium tetrachloride under stirring over a period of time of more than 2 hours.

The reduction reaction may be conducted in the presence or the absence of a diluent such as an inert hydrocarbon. However, for reasons of reaction temperature control and safety, the use of a diluent is preferable. In addition, aliphatic hydrocarbons containing a few percent of aromatic hydrocarbons such as benzene and/or toluene, for example, industrial heptane, may also be used as diluents.

When the addition of the reducing agent has been completed, it is preferable to continue the stirring of the reaction system, preferably at a temperature higher than the reduction temperature, for example, within the range of from 0 to X() C. inclusive, in order to complete the reduction reaction.

After the completion of the reduction reaction, the resulting dark brown reduced solid is fully washed with an inert hydrocarbon such as hexane or heptane, which has been adequately dewatered and degassed. whereupon the reduced solid is rcady for the subsequent heat treatment.

2. Heat treatment The heat treatment which is conducted prior to pulverization is cssential for the present invention. It is necessarv to transform. by this heat treatment, the titanium trichloride having a crystal structure into one having a y- crystal structure to produce a titanium trichloride composition containing substantially no crystal structure. Unless this heat treatment is carried out. the subsequent pulverization process will become almost ineffective.

This heat treatment may be carried out by the following two systems: (i) A svstem wherein the reduced solid in a powdery state is heated in an atmosphere of an inert gas such as argon or nitrogen at a temperature within the range of from l()()(? to 200 C, inclusive, preferably of from 150 to 180 C, for from 1 to 10 hours.

(ii) A system wherein the reduced solid in a slurry state in an inactive hydrocarbon solvent is heated at a temperature within the range of from 100 C. to 200 C. inclusive. preferably of from 150 C. to 18()"C. for from 1 to 1() hours.

When the solid undergoes change upon being heat treated. changes in the colour and crystal structure of the solid can he clearlv distinguished. Thus. the colour of the solid changes from dark brown to purplish red or black purple. This is considered to correspond to the transition of the crystal structure of the solid from the form to the y-flrm. The lS-titanium trichloride can be clearly determined by X-rav diffraction spectra because it has diffraction spectra which are distinctly different from those of the other crystal structure at diffraction angles 2 # of I 6.3 and 50.3 . After heat treatment. these diffraction spectra of the [3-form disappear. and diffraction spectra characteristic of the &gamma;-form 'ippear at diffraction angles 2 # of 15.() and S I .3-. Thus. the transition of the crystal structure can be confirmed from the diffraction spectra.

However. in the heat treatment of the present invention. not all of the heat treatment conditions under which such transition of the cr,'stal structure can be confirmed by X-rav diffraction are practicable. The reason for this is that even the heat treated solid. wherein a complete transition of the ss- crystal structure to the &gamma; - crystal structure occurs. and a diffraction pattern characteristic of the ss- modification is not detectable by means of X-ray diffraction analysis, may exhibit a strong diffraction spectrum characteristic of the ss- modification, or form a mixed crystal having the ss- and 6 - crystal structure when it is subjected to pulverization treatment. Such a solid catalyst component exhibiting partially or wholly the ss- crystal structure on pulverization cannot form a catalyst component having a good performance even if it is subsequently subjected to the organic complexing agent and inorganic halogen compound treatments.

The appearance of the ss- modification during the pulverization of the y - modification solid is related not only. to the heat treatment conditions but also the nature or composition of the reduced solid. In other words, not all of the heat treatment conditions under which the transition of the ss- modification to the y - modification occurs are effective in the heat treatment of the present invention. In order to avoid the appearance of the ss- modification during pulverization, an appropriate combination of the preparation conditions of the reduced solid, the heat treatment conditions, and the pulverization conditions should be determined.

More particularly, in the case where the reduced solid contains a relatively large amount of aluminium compounds (for example, when EADC is used as a reducing agent), mere .heat treatment of the reduced solid at a relatively low temperature for a short period of time (155"C, substantially 2 hours) leads to satisfactory effects of pulverization treatment without the occurrence of the ss- modification after the pulverization. On the other hand, when the reduced solid contains a small amount of aluminium compounds (for example, when DEAC is used as a reducing agent), heat treatment must be conducted at relatively high temperatures and/or for a long period of time; otherwise, the ss- modification appears during the pulverization, damaging the pulverization effect. In addition, heat treatment at a temperature above 200"C is unfavourable because the reduced solid is chemically affected.

Now, referring to the connection with pulverization conditions, when a strong pulverization treatment is effected, the heat treatment should be conducted under as severe conditions as possible provided the reduced solid is not chemically affected. Conversely, in the case where a mild pulverization is effected, a relatively mild heat treatment may be used.

As stated above, in the process for producing the titanium trichloride composition according to the present invention, the practice of heat treatment under conditions such that the transition of the ss- modification to the y- modification occurs is a necessary condition but not a sufficient condition.

In accordance with the process of the present invention, heat treatment conditions should be determined in relation to a combination of the reduction method of the prior step and the pulverization conditions of the subsequent step in order to attain the desired object. In general, the heat treatment conditions should preferably be chosen from within the temperature range of 150 to 2000C and the period range of 1 to 10 hours.

3. Pulverization It is considered that, among the various properties of the titanium trichloride catalyst component, the properties which are considered to have an influence on the polymerization activity of the final catalyst are the surface area, the crystal state, the state of formation of a lattice defect and the state of aggregation of a crystallite. It will be easily conjectured that these properties are largely influenced when the titanium trichloride catalyst component is pulverized.

X-ray diffraction analysis indicates that, while the reduced solid when heat treated exhibits a very sharp diffraction spectrum, indicating that the y- crystal structure thereof is relatively complete, it gives only a broad diffraction spectrum after the pulverization thereof. This indicates that, when the heat treated solid is pulverized, the y- crystal structure of the solid is almost completely destroyed into a 6- or amorphous crystal structure. Observation of microphotographs of the pulverized solid also indicates that the solid particles have been irregularly destroyed.

However, notwithstanding that the properties of the solid have been largely changed by pulverization as stated above, the solid subjected to only the treatments up to the pulverization step in a series of treatments exhibits only a very low performance when it is used as a titanium trichloride catalyst component'.

On the other hand, if the titanium trichloride composition after the heat treatment is subjected to the complexing agent and halogen compound treatments without pulverizing the composition, the composition also exhibits only a low performance when used as a catalyst component. It is considered that the heat treatment and the subsequent pulverization treatment cause the effects of the subsequent complexing agent and halogen compound treatments to be exhibited to a larger extent as compared with mere complexing agent and halogen compound treatments of the reduced solid.

In the pulverization process, it is particularly to be noted that, while the prior process of heat treatment changes the crystal structure of the titanium trichloride from the ss-modification to the y-modification to produce a crystal structure substantially free of the ss-modification, the ss- crystal structure may again appear depending on the pulverization conditions. This is related to a newly observed phenomenon wherein, when a heat treated solid in which the diffraction spectra characteristic of the ss- crystal structure have disappeared, and a complete transition of the ss- modification to the y-modification has been verified by X-ray diffraction analysis is pulverized, the ss-modification may again be detected by X-ray diffraction analysis depending on the pulverization conditions.

In this case, the titanium trichloride, composition containing the ss- crystal structure produced by the pulverization does not form a catalyst component having a high activity even if it is subjected to the subsequent complexing agent and halogen compound treatments. When titanium tetrachloride is chosen, for example, from among various halogen compounds, it is possible eventually to convert the crystal structure of the titanium trichloride composition into the y- or 5- crystal structure, which is a desirable crystal structure as a stereospecific polymerization catalyst, by choosing appropriate conditions for the titanium tetrachloride treatment. However, such a method cannot produce a solid catalyst component having a high activity as is prepared according to the process of the present invention.

In the case where metal halides other than the titanium tetrachloride are used, the treatment of the titanium trichloride composition containing the ss- crystal structure does not always eventually produce a solid component having the 5- or amorphous crystal structure which is preferred as a catalyst component. It is important for the production of a highly active catalyst according to the process of the present invention that the titanium trichloride composition should possess the 5 - or amorphous crystal structure after the pulverization and retain the same crystal structure after the complexing agent and halogen compound treatments.

Even if the reduced solid (3-modification) is directly pulverized and subjected to the complexing agent and halogen compound treatments without carrying out the heat treatment, a titanium trichloride catalyst component having a good performance cannot be obtained, although this is estimated from the above-mentioned results to some extent. By X-ray diffraction analysis, we have observed that a ss- titanium trichloride composition seems to undergo little destruction of its crystal structure eve titanium trichloride composition having a o- crystal structure with good reproducibility if it is pulverized within 24 hours under the same pulverization conditions. In this case, a 48 hours' period of pulverization produces for the first time a mixed crystal of 6- and ss- crystal structures, and this condition begins to come within an unstable range of pulverization conditions.

All pulverizations for a period of time of not less than 72 hours result in a ss- crystal structure. Further, the solid which has been heat-treated at a temperature of 1600C for 8 hours does not exhibit any ss- crystal structure even after 48 hours of pulverization, and the crystal structure of the solid is destroyed and rendered into an amorphous state, but the titanium trichloride is distinguished to be a 6- modification. On the other hand, when EASC or EADC is used as a reducing agent, the solid which has been heat-treated at a temperature of 155"C for 2 hours does not show the occurrence of a crystal structure even after 24 hours of pulverization and provides the effects of the present invention.

As is apparent from the foregoing, the pulverization conditions suitable for providing the effects of the present invention may be determined by combining the conditions of the reduction-heat treatment-pulverization in various forms. However, it is very complicated and difficult quantitatively to represent a practicable range of pulverization conditions in relation to the various factors. Generally, when pulverization is conducted as thoroughly as possible within the range wherein no ss- crystal structure appears, the effects of the present invention can be more fully expected. However, it is of course necessary to consider the fact that the catalytic performance is influenced not only by pulverization conditions but also by the method for preparing the reduced solid and the heat-treatment conditions (even if pulverization is carried out under the same pulverization conditions within which no ss- structure appears).

In conclusion, the suitable conditions are that the heat treatment should be carried out at a temperature of from 150 to 1800C within 10 hours, and that pulverization should be carried out in a period within the range of from 10 to 72 hours depending upon the nature of the reduced solid.

In addition, the pulverization-treated solid should contain absolutely no ss- crystal structure.

As previously mentioned, various complex factors are involved in the determination of pulverization conditions. Thus, needless to say, it is desirable that the pulverization conditions should be determinable irrespective of various factors other than the pulverization factors.

We have found that, when the heat treated solid is ground together with titanium tetrachloride, even under conditions such that a ss- crystal structure appears, it is possible to prevent the formation of the ss- crystal structure. Thus, the co-pulverization of the heat-treated solid in the presence of titanium tetrachloride in order to prevent the ss- crystal structure from occurring during the pulverization is also one of the embodiments wherein "pulverization is conducted under the condition such that no ss- crystal structure appears".

The quantity of the titanium tetrachloride to be added during the pulverization treatment is generally in the range of from 0.03 to 0.3 mole, preferably from 0.05 to 0.2 mole, per mole of titanium trichloride. The use of an excessively large quantity of the titanium tetrachloride causes the sticking of the mass to the pot during the pulverization and is, therefore, unfavourable.

The reason why the formation of the ss- crystal structure can be prevented by the co-pulverization with the titanium tetrachloride is not fully clear. However, the appearance of such a titanium tetrachloride effect is a phenomenon characteristic of a solid prepared by reducing titanium tetrachloride with an organoaluminium compound because the formation of the ss- crystal structure does not occur during pulverizing in the case of a solid prepared by reducing titanium tetrachloride with metallic aluminium.

The co-pulverization with titanium tetrachloride is superior to the pulverization of the heat treated titanium trichloride composition by itself in that the former enlarges the range of the reduced solids which can be supplied to the catalyst preparation and the practicable ranges of heat treatment and pulverization conditions. whereby the range of combinations of the treatment conditions to be determined between the reduction - heat treatment pulverization interrelation is further widened and the freedom of choice for treatment conditions is increased.

For example. a solid prepared by reducing titanium tetrachloride with DEAC and by heat-treating the reduced solid at a temperature of from 155 to l6()0C for 2 hours exhibits the ss- crystal structure when it is ground by itself for 24 hours, whereas it does not exhibit any formation of the ss- crystal structure even after a 48 hours' pulverization when it is ground together with titanium tetrachloride at a molar ratio of TiCI4 to TiCI3 of 0.1:1.

When the pulverization of the reduced solid bv itself requires approximately 48 hours of pulverization. the heat treatment should be conducted with sufficient thoroughness to ensure the transition of the crystal structure. In contrast, in the above-mentioned co-pulverization, the 48 hours of pulverization can be carried out even with a relatively mild heat treatment. Of course, the co-pulverization with titanium tetrachloride may be carried out under the respective treatment conditions which are applicable to the pulverization of the reduced solid by itself. However, the titanium tetrachloride co-pulverization process can produce a titanium trichloride catalyst component having a high performance even under conditions such that this catalyst component cannot be prepared by the singlematerial pulverization process.

These expanded individual treatment conditions relating to the titanium tetrachloride co-pulverization process should also be determined in relation to the composition of the reduced solid-heat treatment condition - co-pulverization conditions. That is, in all the cases where the co-pulverization with titanium tetrachloride is carried out, the formation of the ss- crystal structure is not always avoided, but the range of various conditions under which no ss- crystal structure develops is only widened.

In addition, the co-pulverization with titanium tetrachloride provides no substantial improvement in the catalytic performance of the pulverized material itself in polymerization activity and ability to impart stereo-specificity, and the resulting catalytic performance is substantially similar to that obtained by the single-material pulverization itself and becomes remarkably inferior unless the complexing agent and halogen compound treatments are subsequently conducted. Even in the case where the subsequent complexing agent and halogen compound treatments are carried out, the co-pulverization may sometimes provide a solid catalyst component of higher performance than that obtained by the single-material pulverization, but there is no great difference between the two.

Accordingly, it should be understood that the outstanding effect of the titanium tetrachloride co-pulverization method is that the method makes possible the production of a titanium trichloride catalyst component with high reproducibility and stability under a wide range of reduction-heat treatment-pulverization conditions.

The titanium trichloride contained in the pulverized mass thus obtained is of o-modification or amorphous in crystal structure due to the transition from the T modification. However. it may contain a small amount of the r - crystal structure provided that it contains substantially no ss- titanium trichloride.

4. Complexing agent treatment The complexing agent which may be used in the complexing treatment of the present invention includes various electron-donor compounds containing at least one atom consisting of oxygen. nitrogen. phosphorus or sulphur. Illustrative of such compounds are alcohols, esters, ethers, ketones and amines. In particular, the ethers provide good results.

Examples of the ethers include diethyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl ether, di-n-hexyl ether. anisole, diphenyl ether, diethylene glycol dimethyl ether, diethylene glycol mono-ji-butyl ether, or mixtures thereof.

The quantity of the complexing agent to be used is generally in the range of from 0.3 to 3.0 moles. preferably 0.3 to 2.0 moles, per mole of titanium trichloride. The titanium tetrachloride co-pulverization method has an optimum quantity ratio of the complexing agent at a higher "complexing agent/TiClR ratio" than the single-material pulverization method.

The complexing treatment can be suitably carried out at from room temperature to 100"C for from 30 minutes to 4 hours. It is also desirable that the complexing treatment should be conducted in the presence of an inactive hydrocarbon solvent. Following a thorough washing step. the complexing agent-treated titanium trichloride is then subjected to a halogen compound treatment.

In addition. the titanium trichloride composition which has been subjected to only the processing up to the complexing treatment exhibits only a very low catalytic performance.

5. Halogen compound treatment The titanium trichloride composition subjected to the complexing treatment as stated above is then treated with a metal halide having a Lewis acidity or an inter-halogen compound.

(1) Metal halide compound treatment Examples of the metal halide compound include ZnX2, HgX2, BX3, AlX3, GaX3, SiX4, GeX4, SnX4, SnX2, PX5, PX3, SbX5, SbX3, SeX4, TeX4, TiX4, TiX3, ZrX4, VX4, VX3, MoX5, WX5, CoX@, and NiX2, where X represents F, Cl, or Br. As a halogen, chlorine is preferred. Furthermore. as compounds TiCI4, TeCI4. SEMI, and SbCl3 are preferred. These metal halide compounds may be used singly or in mixtures with one or more of the other above-mentioned compounds.

When titanium tetrachloride, for example, is used as metal halogen compound, the treatment may be carried out in the presence or the absence of a diluent at from room temperature to 100 C for from 30 minutes to 5 hours. The diluents usable for this treatment include aliphatic, alicyclic or aromatic hydrocarbon compounds having from 1 to 12 carbon atoms, and halogenated hydrocarbon compounds having from 1 to 12 carbon atoms. The use of the halogenated hydrocarbon diluents produces good results. It is preferred that, when the concentration of the titanium tetrachloride is high, a relatively low treatment temperature should be used, and, on the other hand, when the concentration of the titanium tetrachloride is low, a high treatment temperature should be used. In general, from 0.005 to 10 moles, preferably from 0.05 to 1 mole of the metal halide per mole of titanium trichloride is used.

The X-ray diffraction analysis of the resulting solid catalyst component after treatment and washing indicates that the titanium tetrachloride treatment results in crystal growth of the solid. This is particularly conspicuous at a higher concentration of the titanium tetrachloride or a higher temperature of treatment. This crystal growth adversely affects the catalytic performance of the titanium trichloride composition. Accordingly, the preferred conditions for the titanium tetrachloride treatment are those under which no crystal growth occurs. These treatment conditions may be determined on the basis of the degree of crystal growth in relation to the concentration of titanium tetrachloride - the treatment temperature - the treatment time.

Under these circumstances, in the case of the treatment with titanium tetrachloride, the treatment conditions are relatively limited because of the occurrence of the unfavourable phenomenon of crystal growth. However. if the other metal halide compounds are used, a broader range of treatment conditions may be used. In this case, if a treatment at an excessively high temperature for a long period of time is carried out. the crystal growth also occurs, and, thus, such treatment conditions are not favourable. The treatment conditions under which the desired effects thereof are obtained will be readily determined by those skilled in the art. In all cases, the treatment conditions under which no crystal growth occurs should be adopted.

If a solid metal halide such as aluminium chloride is used, it is generally used in a suspended state in an inactive solvent. Moreover, such a solid metal halide may be used by partially dissolving it in a solvent such as an aromatic hydrocarbon in which it has a relatively high solubility. Furthermore, a complexed solution of a metal halide compound in an electron-donor compound may be brought into contact with a titanium trichloride solid component. In addition, when the metal halide compounds are solids, these metal halide compounds may be used in a finely divided form in order to ensure good contact with the solid titanium trichloride component to be treated and high reactivity with the complexing agent, such as ether, remaining in the solid component.

(2) 111tellqalogel1 cattipautid tl-eAhtlel1t The titanium trichloride composition subjected to the complexing agent treatment described above is treated with an interhalogen compound which is preferably a compound having the formula XYn, wherein X and Y respectively represent an different halogen atom, and n is an integer of 1, 3, 5 or 7, instead of the metal halide compound treatment, Examples of such interhalogen compounds are CIF, BrF, IF, BrCl, ICI, IBr, CIF3, BrF3, IF3, IClR (I,CI,). ClFs. BrF5. IF and IF7. The compounds ICI?, and ICI are preferred.

The interhalogen compound displays sufficient effectiveness even when it is used in a small quantity. The interhalogen compound is used in a molar ratio to the titanium tnchloride within the range of from 0.005:1 to ().2:1, preferably from 0.005:1 to 0.1:1.

The treatment with the interhalogen compound is ordinarily carried out in the presence of a diluent at from room temperature to 15() C for a period of from 30 minutes to 10 hours.

The diluents suitable for use in this treatment are aliphatic. alicyclic or aromatic hydrocarbon compounds having from 1 to 12 carbon atoms or halogenated hydrocarbon compounds having from I to 12 carbon atoms. The use of the halogenated hydrocarbon diluents produces good results.

The interhalogen compound treatment results in remarkable advantages simultaneously with respect to both the catalytic activity and the stereospecificity of the resulting catalyst component.

6. Polymerization of olefins The titanium trichloride composition prepared in the manner described above is combined with the organo-aluminium compound having the formula AlRnX3-n, wherein n is a value in the range of from 1 to 3, X represents a halogen and R represents a hydrocarbon radical having from I to 1() carbon atoms. to produce a catalyst for stereospecific polymerization of &alpha;-olefins. The organo-aluminium compound is used with a weight ratio relative to the titanium trichloride composition of 0.5:1 to 100:1, preferably 1:1 to 30:1.

Polymerization of olefins may be carried out by a slurry polymerization method using an inert hydrocarbon such as hexane, heptane or cyclohexane as a solvent; a liquid phase polymerization method using a liquefied monomer as a solvent; or a gas phase polymerization method wherein a monomer is present as a gaseous phase. The polymerization may be carried out in a continuous process or in a batch process. The polymerization temperature is ordinarily in the range of from 30 to 120 C, preferably from 50 to 100 C. The polymerization pressure is ordinarily in the range of from atmospheric pressure to 100 atmospheres, preferably from atmospheric pressure to 50 atmospheres.

The a-olefins which may be polymerized singly or copolymerized in the presence of the catalyst of the present invention include ethylene, propylene, 1-butene and 4 methylpentene-1. The molecular weight of the resulting polymer is adjusted by any of various known processes using hydrogen or diethylzinc.

7. Experimental Examples Example 1 (1) Preparation of titanium trichloride catalyst component (i) Reduction of titanium tetrachloride 90 ml of hexane and 22.5 ml of titanium tetrachloride were placed in a 500-ml four-necked flask equipped with a stirrer. Then, a solution of 75 ml of hexane and 25.3 ml of DEAC was continously dropped into the flask under an atmosphere of argon for over 4 hours through a Widmer apparatus. The reaction solution was kept at a temperature of 1 C.

After the completion of the dropping, stirring was continued at that temperature for 15 minutes. after which the temperature was raised to 650C. and the solution was stirred at that temperature for an additional hour to complete the reaction.

The reaction mixture was left standing. whereupon a black-brown solid was obtained.

This solid was washed five times (by decantation). each time with a l()-ml portion of hexane.

(ii) Heat treatment A flask containing a slurrv of the black-brown solid obtained at (i) above was immersed in an oil bath to remove the solvent by evaporation to dryness. The solid was heated in an atmosphere of argon at a temperature of 155 C for 2 hours. During this heat treatment, the colour tone of the solid changed from black-brown to purplish red or dark purple.

After the heat treatment. a portion of the solid was removed and subjected to an X-ray diffraction measurement. The solid displaved a sharp diffraction spectrum at an angle 20 of 15.00 and a spectrum characteristic of a T - crystal structure of titanium trichloride at an angle 26 of 51.3 . As a result. the solid was confirmed to be a T - titanium trichloride composition of high crystallinity containing no - crystal structure.

(iii) Titanium tetrachloride co-plz eri,atiosl treatment 15g of the heat-treated solid obtained in stage (ii) above and 0.83 ml of titanium tetrachloride were charged into a pot of a vibrating mill in a dry box under an atmosphere of gaseous argon. The heat-treated solid contained an aluminium component in a molar ratio relative to the titanium component of 0.24:1. On the assumption that the aluminium component was AlCl3, the added TiCl4 had a molar ratio of 0.092:1 with respect to the TiCI2, contained in the solid.

The pulverization in the vibrating mill was carried out under the following conditions: Volume of pot I litre Apparent volume of ball 0.8 litre Diameter of ball 12.7 mm Vibration frequency 1,410 VPM Vibration amplitude 3.5 mm Pulverizing time (at room temperature 48 hours (iv) Complexing treatment After confirmation by X-ray diffraction analysis of the fact that the pulverized material obtained in stage (iii) above contained no - titanium trichloride, 10g of the solid sample were subjected to a complexing treatment. The complexing treatment was carried out by complexing a suspension of 10g of the sample in 50 ml of hexane with 16.2 ml of diisoamyl ether (a molar ratio of isoamyl ether to TiC13 of 1.49:1) at a temperature of 35"C for 2 hours.

After the completion of the reaction, the reaction mixture was left standing and then washed five times, each time with a 50-ml portion of hexane, by decantation.

(v) Halogen compound treatment After almost all of the supernantant liquid of the solid slurry obtained at (iv) was removed, 30 ml of hexane and 20 ml of titanium tetrachloride (TiCI4 = 40% by volume) were added to the remaining solid slurry, and the resulting mixture was stirred at a temperature of 650for 2 hours to provide an intimate contact between the TiCI4 solution and the solid component.

When the treatment had been completed, the solid component was again washed five times, each time with a 50-ml portion of hexane, by decantation. Finally, the resulting solid component was subjected to vacuum evaporation to remove the solvent therefrom, whereby a powdery titanium trichloride composition, i.e., a titanium trichloride component, was obtained.

(2) Polymerization of propylene (gas-phase polymerization) 20g of polypropylene powder as a catalyst dispersing agent was introduced into an autoclave having a capacity of 1 litre and equipped with a stirrer. The autoclave was subjected to evacuation while it was heated, so that the dispersing agent was degassed to a sufficient degree and dried. Following this, catalyst components were introduced into the autoclave under an atmosphere of a propylene gas in the following order: (i) DEAC (diethylaluminium chloride) 150 mg (ii) the titanium trichloride catalyst component obtained in stage (v) above 30 mg wherein the weight ratio of DEAC to the titanium trichloride composition was 5:1.

1000 ml of hydrogen were further introduced into the autoclave at room temperature and under atmospheric pressure. The reaction mixture was polymerized for 3 hours while propylene replenished in a quantity such that the pressure of the propylene in the autoclave at a temperature of 75"C was maintained at 25 kg/cm2 G.

When the autoclave was opened after purging of the gaseous propylene, 284 g of a polymer were obtained. Deduction of 20 g of the initially added dispersing agent polymer from 284 g leaves 264 g as the quantity of the polymer produced by the polymerization.

Accordingly. the yield per unit of titanium trichloride catalyst component [the yield per catalyst (gram of the polymer per gram of the titanium trichloride composition)| was 8,800.

The stereospecificity (II) of the polymer was found to be 96.7% by a boiling heptane extraction methqd (correction was made to the dispersing agent).

Compa)ative Examples 1, 2 and S In order to indicate that the process of the present invention produces a solid catalyst component which is superior in performance than that obtained by known methods for preparing the solidscatalyst including no heat and pulverization treatments. the following comparative experiments were conducted.

(1) Preparation of titanium trichloride catalyst component.

(i) Reduction of fltaniuiii tetrachloride In each of the experiments. the entire procedure described in Example 1 was followed except as noted below.

(ii) Coniplexitig ticatinetit In each of the experiments. a complexing treatment was carried out according to the procedure described in Example l except that diisoamyl ether was used in a molar ratio of 0.7:1. 0.9:1. and 1.5:1. respectively. with respect to the titanium trichloride contained in the reduced solid.

(iii) Halogen compound treatment In, each of the experiments, treatment with titanium tetrachloride was carried out under the same conditions as those described in Example 1.

(2) Polymerization of propylene In each of the experiments following the procedure described in Example 1, the gas-phase polymerization of propylene was carried out by using the titanium trichloride composition obtained in the above described manner.

The results obtained are set forth in Table 1 just below as follows: TABLE 1 Complexing Result of polymerization of Comp.Ex. treatment propylene Yield per cat. Stereospecificity 1 0.7 4,300 95.0 2 0.9 5,900 96.7 3 1.5 3,800 95.7 Example 2 This example is set forth to indicate that the titanium trichloride catalyst component obtained by the process of the present invention exhibits excellent performance not only in gas-phase polymerization but also in liquid-phase polymerization. A titanium trichloride catalyst component was prepared and evaluated for liquid-phase polymerization of propylene in the following manner.

(1) Preparation of titanium trichloride catalyst component A titanium trichloride catalyst component was prepared according to the procedure described in Example 1 except that: the heat treatment was carried out at a temperature of 1600C for 8 hours; the complexing treatment was carried out in a molar ratio of isoamyl ether to TiCI3 of 1.50:1; and the halogen compound treatment with titanium tetrachloride was carried out at a temperature of 70"C for 2 hours by using a 30%, by volume, solution of TiCI4 in hexane.

(2) Polymerization of propylene (liquid-phase polymerization) 300 mg of DEAC and 17mg of the titanium trichloride catalyst component prepared in stage (1) above were introduced in that order into an autoclave having a capacity of 1 litre and equipped with a stirrer, under an atmosphere of propylene gas. 'Then, after 1 liter of hydrogen was further introduced into the autoclave at room temperature and atmospheric pressure, 800 ml of a liquefied propylene monomer were added thereto, and polymerization was started. The polymerization was continued at a temperature of 75"C for 3 hours. After completion of the polymerization, the remaining monomers were purged, whereupon 213g of a polymer were obtained.

The yield per catalyst was 12,500 and the stereo-specificity of the polymer was 94.9% Example 3 The preparation of a reduced solid and the heat treatment of the solid were conducted under the conditions and by the procedure described in Example 1. The pulverization of the heat-treated solid was carried out by a single pulverization process without the use of titanium tetrachloride. The pulverization conditions were similar to those described in Example 1 except that the pulverizing time was 24 hours (the crystal structure of the pulverized solid was of T or o-modification). The complexing agent and titanium tetrachloride treatments of the pulverized material were carried out according to the procedures described in Example 1 except that the molar ratio of diisoamyl ether to titanium trichloride was 1.3:1. Thus, a titanium trichloride catalyst component was prepared. Using this catalyst component, gas-phase polymerization of propylene was carried out under the same conditions as those described in Example 1.

When correction was made to the polymer used as a dispersing agent for the titanium trichloride catalyst, the yield per catalyst and the stereospecificity of the resulting polymer were 6,700 and 96.6C/c. respectively.

Comparative Examples 4 to 9 These comparative examples show that in accordance with the present invention, it is necessary and important to carry out the heat treatment and the pulverization treatment in a particular stage of the process for preparing a titanium trichloride catalyst component and in a continuous manner, and that pulverization is highly effective, but a mere combination of known techniques cannot produce a solid catalyst component producing the excellent performance of the solid catalyst component obtained by the present invention.

The results obtained by these comparative examples are shown in Table 2 below as follows: TABLE 2 Comp. Ex. Process for preparing a titanium trichloride Result of polymerization catalyst component a) of propylene b) Yield per catalyst Stereospecificity 4 Reduction-heat treatment-complexing treatment-TiCl4 treatment-pulverization 1,500 95.7 5 Reduction-heat treatment-complexing treatment-pulverization-TiCl4 treatment 2,400 95.6 6 Reduction-complexing treatment-heat treatment -pulverization-TiCl4 treatment trace 7 Reduction-heat treatment-complexing treatment -pulverization-complexing treatment-TiCl4 treatment 2,700 90.4 8 Reduction-heat treatment-complexing treatment-TiCl4 treatment 2,400 91.5 9 Reduction-complexing treatment-TiCl4 treatment-pulverization 3,500 97.5 Note: (a) The respective treatment conditions of comparative Examples 4 to 8 are the same conditions as those described in Example 3. In Comparative Example 9, the titanium trichloride composition prepared by the known method described in Comparative Example 1 was pulverized under the same conditions as those described in Example 3.

(b) The polymerizations are all the same gas-phase polymerization of propylene as that described in Example 1. All numerical values are those obtained after correction was made for the dispersing agent polymer.

Comparative Examples 10 to 15 These comparative examples show that a titanium trichloride composition obtained by pulverizing a titanium trichloride composition having a ss- crystal structure and a titanium trichloride composition containing a ss- crystal structure after pulverization, even if it is of ytype crystal structure prior to pulverization, cannot produce a titanium trichloride composition having a good catalytic performance, even if they are subjected to complexing agent and halogen compound (titanium tetrachloride) treatments.

The results are shown in Table 3 below as follows: TABLE 3 Process for preparing titanium trichloride catalyst component Result of polymerization propylene *5 Complexing TiC4 Heat treatment Pulverization treatment treatment treat- Yield per Stereospecific Comp. Reduc- *3 ment*4 catalyst Ex. tion 1 Tempera- Time Pulverization Time Crystal Mole ratio ture (hour) style (hour) structure diisoamyl ( C) after pul- ether to verization TiCl3 10 " none single 48 ss 14 " 170 67.2 pulverization 11 " 155 - 160 2 " 32 ss 1.35 " 3,800 97.1 12 " " " " 72 ss 1.4 " 1,500 94.7 13 " 165 - 170 " " 96 ss 1.3 " 1,100 94.1 14 " 170 4 " 43 ss + # (mixed 1.0 " 1,700 crystal 15 " 160 TiCl4 *2 72 ss + # co-pulveri- (mixed 1.3 " 2,900 96.7 zation crystal) Note: *1: A reduced solid was prepared according to the procedure described in Example 1.

*2: The quantity of the titanium tetrachloride used in the co-pulverization is represented as the molar ratio of TiCl4 to TiCI3 of 0.1:1.

P3: The other conditions for the complexing treatment are the same as those described in Example 1.

*4: The conditions described in Example 1 were used.

P5: The polymerization conditions described in Example 1 were used (correction was made for the dispersing agent).

Comparafive Examples 16 to 18 These comparative examples show that a titanium trichloride catalyst component subjected to only a heating and pulverization treatment and a titanium trichloride catalyst component subjected to only a heating and complexing treatment can provide only a titanium trichloride catalyst component of a remarkably low catalytic performance.

The results are shown in Table 4 below as follows: TABLE 4 Crystal Result of polymerization Comp. Process for preparing a titanium trichloride structure of propylene Ex. catalyst component *1 after pulveriza- Yield per Stereospecificity tion catalyst 16 Reduction-heat treatment-single pulverization (160 C, 8 hours) (48 hours) # 700 86.6 17 Reduction-heat treatment-TiCl4/ co-pulverization (160 C, 8 hours) (48 hours, TCl4/ # 1,000 84.8 TiCl3=0.1) Reduction-heat treatment-TiCl4 co-pulverization- # Complexing treatment 18 TiCl4 (160 C, 8 hours) (48 hours, = 0.2) 900 81.6 TiCl3 Isoamyl ether = 1.4) TiCl3 @) The treatment conditions other than those described in Table 4 are similar to those described in Examples 1 and 3.

Example 4 A reduction process was carried out under the conditions described in Example 1 except that EASC (ethylaluminium sesquichloride) was used as a reducing agent for titanium tetrachloride, and the molar ratio of EASC to TiCI4 was 2:1. The resulting reduced solid was heat-treated at a temperature of 155 to 1600C for 2 hours. The heat-treated solid was subjected to a single pulverization treatment for 24 hours. The pulverized solid had a crystal structure and a molar ratio of EASC to TiCIX of 0.59:1. The complexing agent and halogen compound (titanium tetrachloride) treatments of the pulverized solid were carried out according to the procedures described in Example 1 except that the molar ratio of diisoamyl ether to titanium trichloride was 1.6:1.

By using the titanium trichloride catalyst component thus prepared, gas phasepolymerization of propylene was carried out in the same manner as described in Example 1.

The yield per catalyst was 5,000, and the stereo-specificity of the resulting polymer was 97.6%.

Example 5 The preparation of a titanium trichloride catalyst component and a polymerization were carried out according to the procedure described in Example 4 except that EADC (ethylaluminium dichloride) was used in a molar ratio of EADC to TiCI4 of 1:1 as a reducing agent for titanium tetrachloride, and the molar ratio of isoamyl ether to TiCI3 was 1.4:1 in the complexing treatment.

The yield per catalyst was 6,900, and the stereospecificity of the resulting polymer was 97.9%.

Examples 6 to 10.

A reduced solid was prepared in the same manner as described in Example 1. The reduced solid was heat-treated at a temperature of 160"C for 8 hours, and the titanium tetrachloride co-pulverization treatment of the heat-treated solid was carried out with various molar ratios of TiCI4 to TiCI3 for 48 hours. The complexing agent and halogen compound (titanium tetrachloride) treatments of the pulverized solid were carried out according to the procedures described in Example 1 except that the amount of the complexing agent was varied. Thus, a titanium trichloride catalyst component was obtained. The polymerization evaluation for the catalyst component was carried out according to the same liquid phase polymerization of propylene as described in Example 2.

The results are shown in Table 4 below as follows: TABLE 4 TiCl4 co-pulverization treatment Complexing Result of polymerization treatment Molar ratio of Crystal structure Molar ratio of iso- Yield per Stereospecifi TiCl4 to TiCl3 after pulverization amyl ether to catalyst city TiCl3 Example 7 0.05 # 1.3 9,400 96.6 Example 8 0.10 " 1.4 10,800 96.6 Example 9 " " 1.5 12,100 95.9 Example 10 0.15 " 1.5 10,300 96.3 Example 11 " " 1.7 10,100 96.2 Examples 11 to 14.

A reduced solid was prepared in the same manner as described in Example 1 above. The reduced solid was heat-treated at a temperature of 1600C for 8 hours. The titanium tetrachloride co-pulverization treatment of the heat-treated solid was carried out with a molar ratio of TiC14 to TiCI3 of 0.1:1. The resulting titanium trichloride composition having a crystal structure was subjected to complexing treatment with a mole ratio of diisoamyl ether to TiCl3 of 1.5:1. Then, the halogen compound (titanium tetrachloride) treatment of the resulting composition was carried out under various conditions to produce titanium trichloride catalyst components. The respective titanium trichloride catalyst components were evaluated for performance according to the propylene liquid-phase polymerization process as described in Example 2.

The results are shown in Table 6 below as follows: TABLE 6 Lewis acid (TiCl4) treatment Result of polymerization of propylene Concentration (% by volume) Temperature ( C) Time (hour) Yield per catalyst Stereospecificity Example 11 20 70 4 8,400 97.9 Example 12 30 65 4 11,000 97.7 Example 13 40 40 2 7,500 94.3 Example 14 100 room 4 6,800 95.6 temperature Exattiple 15 A reduced solid was prepared in the same manner as described in Example 1. The reduced solid was heat-treated at a temperature of 1600C. for 8 hours and then subjected to a single pulverization treatment for 24 hours. The pulverized solid (6 - TiCI) was subjected to a complexing treatment by using diphenyl ether (the molar ratio of diphenyl ether to TiCI3 being 1.2:1. The halogen compound (titanium tetrachloride) treatment of the resulting solid was carried out according to the same conditions as those described in Example 1. Thus. a titanium trichloride catalyst component was obtained. Using this catalyst component. gas-phase polymerization of propylene was carried out according to the procedure described in Example I. The yield per catalyst was 2,500 and the stereospecificity of the resulting polymer was 95.2%.

Example 16 The complexing agent-treated solid obtained by effecting the entire procedure described in Example 2 up to the point of the complexing treatment was subjected to a halogen compound treatment by using tellurium tetrachloride (TeCI4).

The treatment with TeCI4 was carried out by adding 0.4 g of TeCI4 purified by a recrystallization method to the complexing agent-treated solid suspended in 100 ml. of a dried and degassed chlorobeozene solvent (with a weight ratio of TeCI4 to treated solid of 0.04:1). and heating the resulting mixture at a temperature of 85 C for 2 hours.

After the treatment. the solid component was washed with 100 ml. portions of chlorobenzene for the first two times and then washed three times with 100-ml. portions of hexane by means of decantation.

Polymerization of propylene was carried out by using 300 mg of DEAC and 10 mg of the titanium trichloride catalyst component according to the liquid phase polymerization method described in Example 2.

The yield per catalyst was 15.500 and the stereo-specificitv of the resulting polymer was 97.2%.

Exaitiple 17 Halogen compound treatment was carried out according to the procedure described in Example 16 except that l.2g of selenium tetrachloride (SeC14) were used as a halogen compound and toluene was used as a treating solvent. After the treatment. the solid component was first washed with 100 ml of toluene and then washed five times each time with 100-ml portion of hexane bv decantation.

Polymerization of propylene was carried out by using 300 mg of DEAC and 15 mg of the titanium trichloride catalyst component according to the liquid phase polymerization method described in Example ' The yield per catalyst was 10.700. and the stereospecificity of the resulting polymer was 97.7%.

Example 18 The procedure described in Example 2 was repeated up to the point where the complexing treatment was completed except that the molar ratio of diisoamyl ether to titanium trichloride was 1.4:1.

The resulting complexing agent-treated solid was suspended in lü() ml of dried and degassed toluene. and 3.0 g of antimony trichloride purified by reduced pressure distillation were added to the suspension. the weight ratio of antimony trichloride to treated solid being 0.3:1. The resulting suspension "'as heated to a temperature of XO"C for 2 hours. After the treatment. the treated solid was first washed with 50 ml of toluene and then washed five times. each time with a m()()-ml portion of hexane.

The polymerization evaluation for the resulting solid was carried out according to the propylene liqiiid phase polymerization method as described in Example 2 except that 200 mg of the titanium trichlofide catalyst component were used. The yield per catalyst was 3,500 and the stereospecificity of the resulting polymer was 96.7% ExattU)k 19 The complexing agent-treated solid obtained as in Example 2 up to the point of the complexing treatment was subjected to the halogen compound treatment by using titanium trichloride. The above titanium trichloride was prepared bv reducing titanium tetrachloride with DEAC. heating the resulting titanium trichloride to effect the transition of its crystal construction. and pulverizing the heat-treated solid for AS hours.

The treatment with the titanium trichloride was conducted by adding 2.()y of the titanium trichloride to a suspension of the complexing agent-treated solid in l()() ml of toluene. the weight ratio of TiCl3 to treated solid being 0.2:1. and heating the suspension at a temperature of 100"C for 2 hours. After the treatment, the resulting suspension was first washed with 100 ml of toluene and then washed four times in total, each time with a 100-ml portion of hexane. The washing was carried out by.a decantation method. Liquid phase polymerization of propylene was conducted according to the procedure described in Example 2.

The yield per catalyst was 4,800, and the stereo-specificity of the resulting polymer was 93.5%.

Example 20 A complexing agent-treated solid obtained as in Example 2 up to the point of the complexing treatment was subjected to halogen compound treatment with the use of aluminium chloride.

The halogen compound treatment was conducted by suspending the complexing agent-treated solid in 100 ml of dried and degassed mesitylene, adding 2.5g of aluminium chloride purified by a sublimation method to the suspension, the weight ratio of AlC13 to treated solid being 0.25:1, and heating the resulting suspension at a temperature of 100"C for 2 hours.- After the treatment, the resulting suspension was washed 5 times each time with a 100-ml portion of a solvent (according to decantation). The first washing was carried out with mesitylene, and the other four washings were all carried out with hexane.

The polymerization evaluation for the resulting catalyst component was carried out according to the propylene liquid phase polymerization process described in Example 2 above.

The yield per catalyst was 4,000 and the stereo-specificity of the resultant polymer was 93.4%.

Example 21 (Slurry polymerization) 500 ml of dried and degassed heptane, 260 mg of DEAC, and 10 mg of the titanium trichloride catalyst component prepared in Example 1 were added in that order to a Widmer apparatus for preparing a catalyst in order to prepare a polymerization catalyst slurry.

An autoclave having a capacity of 1 liter and equipped with a stirrer was repeatedly subjected to several operations of vacuum exhaustion - introduction of gaseous propylene.

The polymerization catalyst slurry was then introduced into the autoclave under an atmosphere of gaseous propylene. 30 ml of hydrogen were added to the autoclave at room temperature and under atmospheric pressure. Polymerization was thereafter continued at a temperature of 70"C for 6 hours while propylene was supplied so as to maintain a propylene pressure of 9 kg/cm2G.

After the propylene gas had been purged, the resulting polymer slurry was withdrawn and filtered off. 115.5g of a solid polymer were obtained. When the solvent of the filtrate was evaporated to dryness, 1.5g of a viscous polymer were obtained.

The yield per catalyst was 11,700.

The stereospecificity (hereinafter referred to as product II) of the solid polymer was found to be 97.8%. according to a boiling heptane extraction method.

Accordingly. the total (II) was 96.6%. polymer which is not dissolved by the heptane extraction Total II = solid polymer + dissolved polymer in polymerization solvent Example 22 The preparation of a catalyst and polymerization of propylene were carried out according to the procedure described in Example 3 except that 30 mg of DEAC were used, the weight ratio of DEAC to titanium trichloride composition being 3:1.

108.3 g of a solid polymer were obtained. 1.7g of a polymer were obtained from the polymerization solvent. The product (II) of the solid polymer was 98.9%.

Accordingly, the yield per catalyst was 11.000. and the total (II) was 97.4%.

Example 23 (1) Preparation of titanium tnchloride catalyst component (i) Redttcaoti of TiC4 atid heat ticatinent 90 ml of hexane and 45.0 ml of TiCl4 were placed in a 50()-ml four-necked flask equipped with a stirrer. Then, a solution consisting of 150 ml of hexane and 50.6 ml of DEAC was continuously dropped into the flask under an atmosphere of argon over 4 hours through a Widmer apparatus. The reaction solution was kept at a temperature of () C. After the completion of the dropping, the stirring was continued at that temperature for 15 minutes.

The temperature was then raised to 650C, and the solution was stirred at that temperature for an additional hour to complete the reaction.

After the reaction mixture was left standing, a black-brown solid was obtained. This solid was washed five times, each time with a 110-ml portion of hexane (by decantation). The resulting titanium trichloride had a crystal structure.

A flask containing a slurry of the black-brown solid was immersed in an oil bath at a temperature of 1500C and heat-treated in an atmosphere of argon for 6 hours. The crystal structure of the solid was converted to the t -modification.

(ii) Titanium tetrachloride co-pulverization treatment 60 g of the heat treated solid obtained in (i) above and 3.3 ml of TiCI4 were charged into a pot of a vibration mill in a dry box in an atmosphere of gaseous argon. These materials were co-pulverized for 48 hours. The other pulverization conditions were similar to those described in Example 1 above.

(iii) Complexing treatment 10 g of the co-pulverized solid sample obtained in (ii) above were subjected to a complexing treatment. The complexing treatment was carried out by suspending 10g of the sample in 50 ml of hexane and adding 14.4 ml of diisoamyl ether to the resulting suspension, the molar ratio of diisoamyl ether to TiCI3 being 1.4:1, to subject the resulting mixture to a temperature of 35"C for 2 hours. After the completion of the reaction, the reaction mixture was left standing and then washed five times each time with a 50-ml portion of hexane (by decantation).

(iv) ICIs treatment After almost all of the supernatant liquid of the solid slurry obtained in (iii) had been removed 100 ml of 1.2-diebloroethane and 0.605 g of iodine trichloride ICY,, the molar ratio of IClR to TiC13 being 0.051:1. wçre added to the remaining solid slurry and the resulting mixture was subjected to the reflux temperature (substantially 75"C) of the solvent for 3.5 hours.

Upon completion of the treatment, the resulting solid component was washed twice with 100-ml portions of 1,2-dichloroethane, and thereafter with 100-ml portions of hexane three times by decantation to yield the desired titanium trichloride catalyst component.

(2) Polymerizntion of propylene (liquid phase pólymerization) 300 mg of DEAC and 15 mg of the titanium trichloride catalyst component obtained in (iv) were introduced in that order into an autoclave having a capacity of 1 liter and equipped with a stirrer in an atmosphere of propylene gas. After 1.2 liters of hydrogen had been further introduced into the autoclave at room temperature and under atmospheric pressure, 700-ml of a liquefied propylene monomer were added thereto and polymerization was started. The polymerization was continued at a temperature of 75"C for 3 hours.

A gradual reduction in pressure was observed for the last thirty minutes of the polymerization operation. which indicated that the polymerization reaction was being carried out in a gas-phase state. However, the polymerization reaction was continued as it was. the final pressure being reduced to 2Skg/cm2 G. When the polymerization was complete. the remaining monomers were purged. 260g of a polymer were obtained. The yield per catalyst was 17.300 and the stereospecificity of the polymer was 97.6%.

Examples 24 to 26 A slurry of the complexing agent-treated titanium trichloride obtained by effecting the treatments described in Example 23 up to the point of the complexing treatment was subjected to ICl. treatment by using different amounts of IC)3. The treatment conditions were similar to those described in part (iii) of Example 23 except that the treatment time was 2 hours.

Polymerization of propylulne was also carried out according to the procedure and conditions described in part (2) of Example 23.

The results are shown in the following Table 7.

TABLE 7 ICl3 treatment Result of polymerization of propylene ICl(g) Molar ratio of Yield per ICl3 to TiCI3 catalyst Stereospecificity Example 24 0.271 0.0230 13,900 95.0 Example 25 0.405 0.0344 15,200 96.0 Example 26 0.945 0.803 17,100 96.8 Example 27 A titanium trichloride catalyst component was prepared according to the procedure and conditions described in Example 23 except that 0.3 g of ICI, the molar ratio of ICI to TiCI3 being 0.0366:1, was used instead of Ill3.

Polymerization of propylene was carried out according to the procedure described in Example 23.

The yield per catalyst was 13,900 and the stereo-specificity of the resulting polymer was 93.6%.

Claims (1)

1. WHAT WE CLAIM IS;

   1. A process for preparing a titanium trichloride composition suitable for use as the transition metal component of a Ziegler-type catalyst, which process comprises the steps of: (i) reducing titanium tetrachloride with an organoaluminium compound to produce a titanium trichloride composition having a ss- crystal structure; (ii) heat treating the resulting titanium trichloride (of form) at a temperature within the range of from 100"C to 2000C., inclusive. to convert the titanium trichloride from the beta to the gamma form, and subsequently pulverizing the heat-treated titanium trichloride, in the presence or absence of titanium tetrachloride to produce a titanium trichloride composition containing titanium trichloride which is amorphous or of delta structure and containing substantially no titanium trichloride having a ss- crystal structure: (iii) treating the resulting pulverized titanium trichloride composition with (an organic) complexing agent; and (iv) treating the resulting titanium trichloride composition with at least one inorganic halogen compound consisting of at least one halide having Lewis acidity and/or at least one interhalogen compound. or any mixture or combination thereof.

   2. A process as claimed in Claim l. in which the organoaluminium compound has the formula: Al Rn ClR " wherein ii is a number satisfying the equation: 0 < ne;3 and R is a hydrocarbon radical having from 1 to 10 carbon atoms.

   3. A process as claimed in Claim 2. in which the organoaluminium compound consists of diethylaluminium chloride. ethylaluminium sesquichloride or ethylaluminium dichloride, or any mixture thereof.

   4. A process as claimed in any one of the preceding claims, in which the reduction temperature is in the range of from -30"C to 30"C.

   5. A process as claimed in any one of the preceding claims. in which the titanium trichloride composition having a ss- crystal structure is heat-treated at a temperature of from 100 to 200"C. under an atmosphere of an inert gas for I to 10 hours.

   6. A process as claimed in Claim 5. in which the titanium chloride composition of ss- crystal structure is heat-treated at 1000C to 1800C.

   7. A process as claimed in any one of the preceding claims. in which the heat-treated titanium trichloride is pulverized for from 10 to 72 hours.

   8. A process as claimed in any one of the preceding claims, in which the heat-treated titanium trichloride is pulverized in the presence of titanium tetrachloride to produce titanium trichloride having substantiallv no titanium trichloride with a lS- crystal structure.

   9. A process as claimed in Claim 8. in which the titanium tetrachloride is in a quantity of from 0.03 to ().3 mole per mole of the titanium trichloride.

   10. A process as claimed in any one of the preceding claims, in which the còmplexing agent is an organic electron donor compound having at least one atom consisting of oxygen, nitrogen, phosphorus or sulphur.

   11. A process as claimed in Claim 10, in which the complexing agent consists of an alcohol, ester, ether, ketone or amine, or any mixture thereof.

   12. A process as claimed in Claim 11 in which the complexing agent is an ether consisting of diethyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl ether, di-n-hexyl ether, anisole, diphenyl ether, diethylene glycol dimethyl ether or diethyleneglycol mono-n-butyl ether, or any mixture thereof.

   13. A process as claimed in any one of the preceding claims in which the complexing agent is in a quantity of from 0.3 to 3.0 moles per mole of the titanium trichloride.

   14. A process as claimed in any one of the preceding claims, in which the complexing is carried out at a temperature of from room temperature to 100"C for from 30 minutes to 4 hours.

   15. A process as claimed in any one of the preceding claims, in which the metal halide compound having Lewis acidity consists of ZnX2, HgX2, BX3, AIR3, GaX3, SiX4, GeX4, SnX4, SnX2, PX5. PX3, SbX5, SbX3, SeX4, TeX4, TiX4, TiX3, ZrX4, VX4, VX3, MoXS, WX5, CoX2 or NiX2, wherein X is a halogen atom consisting of fluorine, chlorine or bromine. to. A process as claimed in Claim 15 in which the metal halide compound having Lewis acidity consists of SbX3, SbX4, TeX4 or TiX4, wherein X is chlorine.

   17. A process as claimed in any one of the preceding claims in which the treatment with the metal halide compound or compounds is carried out in the presence of a diluent at a temperature of from room temperature to 100"C for from 30 minutes to 5 hours.

   18. A process as claimed in Claim 17, in which the diluent is a halogenated hydrocarbon having 1 to 12 carbon atoms.

   19. A process as claimed in any one of the preceding claims in which the quantity of the metal halide is in the range of 0.005 to 10 moles per mole of titanium trichloride.

   20. A process as claimed in Claim 19. in which the quantity of the metal halide is in the range of 0.05 to 1 mole per mole of the titanium trichloride.

   21. A process as claimed in any one of the preceding claims in which the interhalogen compound has the formula: XY wherein X and Y are different halogen atoms, and n is 1 3, 5 or 7.

   22. A process as claimed in Claim 21 in which the interhalogen compound consisting of CIF. BrF, IF, BrCl. ICI. IBr, Coif. BrF3, IF3, ICY3, or 12Cl6, COIFS BrF5. IF5 or IF7.

   23. A process as claimed in Claim 22 in which the interhalogen compound consists of ICI3 or ICI.

   24. A process as claimed in any one of the preceding claims in which the treatment with the interhalogen compound is carried out in the presence of diluent at a temperature of from room temperature to 1500C for from 30 minutes to 10 hours.

   25. A process as claimed in Claim 24. in which the diluent is a halogenated hydrocarbon having 1 to 12 carbon atoms.

   26. A process as claimed in any one of the preceding claims in which the interhalogen is used in a quantity of from 0.005 to 0.1 mole per mole of the titanium trichloride.

   27. A process according to Claim l for producing a titanium trichloride composition substantially as hereinbefore described.

   28. A process according to Claim l for producing a titanium trichloride composition substantially as hereinbefore described with reference to any of the specific Examples.

   29. A titanium trichloride composition whenever produced according to a process as claimed in any one of Claims 1 to 28.