CA1073149A - Process for producing polypropylene - Google Patents

Abstract

PROCESS FOR PRODUCING POLYPROPYLENE

ABSTRACT OF THE DISCLOSURE:
In a process for the polymerization of propylene, a polymer having improved mechanical properties can be obtained in high yields without forming a noticeable amount of an amorphous polymer as a by-product by using a catalyst system comprising (a) a fine granular form of titanium trichloride, (b) an organoaluminum compound, and (c) an organic phosphite having a formula:
P(OR)nX3-2 wherein R denotes a hydrocarbon radical having 1 - 30 carbon atoms, X a halogen atom, and n a number 1 - 3, the titanium being a purple finely granulated solid obtained by precipitation from a homogeneous liquid mixture or solution of titanium trichloride and an ether in the presence of a Lewis acid.

Description

FIELD OF THE INVENT~ONo This invention relates to a pxocess for polymerization of propylene and more particularly, to a process for producing a polypropylene with improved ster~oreglllarity using catalysts having high polymerization activity and catalytic efficiency.
BACKGROUNI) OF THE INVENTION:
It is fundamental and well known in the production of polypropylene to use the so-called Zi.egl~r-Natta cata~ysts consisting of titanium trichloride and an organoaluminum compound. The most conventional method among the pri.or methods uses a particular form of titanium trichloride which is prepared I
by reducing titanium tetrachloride with metallic aluminum :~
and mechanically dividing the reduced proauct in a ball mill or the like. Such catalysts, however, are insuf~icient both in polymerization activity and catalytic efficiency so that the : :
produced polymer is poor in stereoregularity. Therefore, complicated after-treatments are needed to remove the entrained catalyst and amorphous polymer from the produced pol~mer. Catalyst systems which can make the stereo- .
regularity of polymers higher are known. These catalysts com-prise a two-component catalyst of titanium trichloride and an organoaluminum compound and an oryanic phosphite added as a third component. Such catalyst systems increase the stereo-regularity of polymers~ while polymerization activity and catalytic efficiency remain low or may even decrease.

, :`` ~ 3~
I . ':
Concretely~ it is impossibl~ to increase catalytic e~ficiency to a level more than 3000 ~ of polypropylene produced per gram of titanium trichloride. Extensive researches and investigations have been made to improve polymerization activity and catalytic efficiency. However, catal~st systems capable of improving polymerization acti~ity and catalytic e~ffciency as well as stereoregularity have not yet been developedO
SUMMARY OF THæ INVENTIO~:
. __ The present invention relates to a process for poly-merization of propylene in the presence of a catalyst system comprising (a) titanium trichloride, tb) an organo-aluminum compound and (c) an organic phosphite having a formula:

( )n 3-n (1) (wherein R denotes a hydrocarbon radiGal having 1-30 carbon atoms, X a halogen atom, and n a number of 1 - 3). It has been found according to this invention that the yields of polypropylene having high stereoregularity can be improved if the titanium trichloride in the above catalyst system is a finely granulated purple solid obtained by precipitation from a homogeneous liquid mixture or solution of titanium trichloride and an ether in the presence of a Lewis acid.

BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 is a graph showing the particle size distribu-tion of polymer particles obtained in Example 1 and ComparatiYe Exampie 2, the particle size (~) as abscissa and the cumulative ;: : . . .:
., ~ " , , . ; , . ,:

3~

¦ weight (%) o~ particles having larger diameter than the given ¦ value a~ ordinate.

¦ DESCRIPTI~N OF T~IE PREFERRED EMBODIMEMTS
¦ . Titanium trichloride u~ed herein may be any fine-1 granular solid titani~m trichloride which is prepared by precipitation from a homogeneous liquid mixture or solution of titanium trichloride and an e~her. This homogeneous liquid mixture or solution is referred to hereinafter as '~
"the homogeneous liquid" or "the homogeneous liquid comprising titanium trichlor.ide". ~ -The precipitation is preferably carried out in the presence of a hydrocarbon solvent and preferably at a tempera-ture in the range of 20 - 150C.

~073149 ~`
The preparation of the above type of titanium trichlo-ride will be described in detail hereinafter. First of all, for the preparation of a homogeneous liquiid comprising titanium trichloride tTicl3); the following two methods are preferred. I
(A) Titanium tetrachloride is used as a starting material, which is reduced with a particular organo-aluminum compound in the presenc:e of an ether and, if desired, a suitable hydrocarbon solvent.
(B3 Solid titanium trichloride is used as a starting material, which is treated with an ether, if desired, in the presence of a suitable hydrocarbon solvent.
Method (A) will be explained. According to method ~A), titaniumi tetrachloride used as a starting material is subjected to reduction with a particular organo-aluminum compound in the presence of an ether and, if desired, a suitable hydrocarbon solvent to obtain a homogeneous liquid comprising ~itanium ~richloride (TiC13). ;
Any suitable ether ~ay be employed as the ether in method (A~, provided it forms a homogeneous liquid with titanium trichloride. Preferred examples of the !
ether are selected from ethers which are soluble in a hydro~
carbon solvent, for example, ethers having the formula:

:'!1~ ..j 10'~3149 RlOR2 . O~ 2) wherein R and R may be the same or different and represent members selected from the group consisting of alkyl, aralkyl, alkenyl, aryl and alkaryl radicals. Specific examples o the ether include dialkyl ethers such as di~n-amyl ether, di-n-butyl ether, di-n-propyl ether, di-n~hexyl ether, di-n-hsptyl ether, di-n-octyl ether, di-n-decyl ether, di-n dodecyl ether, di-n-tridecyl ether, n-amyl-n-butyl ether, n-amyl isobutyl ether, n-amyl ethyl ether, n butyl-n-propyl ether, n-butyl ;
isoamyl ether, n-ethyl-n-hexyl ether, n-propyl-n-hexyl ether, n-butyl-n-octyl ether, n-hexyl-n-octyl ether, etc.; dialkenyl ethers such as bis(l-butenyl) ether, bis~l-octenyl) ether, bis(l-decenyl) ether, l-octenyl-9-decenyl cther, etc.; diaralkyl ethers such as bis(benzyl) ether, etc.; dialkaryl ether such as bis(tolyl) ether, bis(xylyl) ether, bis(ethyl phenyl) ether, ¦ tolyl xylyl ether, etc.; alkyl alkenyl ethers such as propyl-l-butenyl ether, n-octyl~ decenyl ether, n decyl-1-decenyl l ether, etc.; alkyl aralkyl ethers such as n-octyl benzyl ether, ¦ n-decyl benzyl ether, etc.; alkyl aryl ethers or alkyl alkaryl ~20 ¦ ethers such as n-octyl phenyl ether, n-octyl tolyl ether, n-decyl tolyl ether, etc.; aralkyl alkenyl ethers suah as l-octenyl benzyl ether, etc.; aryl alkenyl ethers or alkaryl alkenyl ethers such as l-octenyl phen~l ether, l-octenyl tolyl ether, etc.; and aralkyl aryl e~hers or aralkyl alkaryl ethers such as benzyl phenyl ether, benzyl tolyl ether, etc.

1073~49 -Among them most preferred are ethers of the formula (2) wherein Rl and R2 represent a linear hydrocarbon radical such as an alkyl and alkenyl radical having more than 3 carbon atoms.
The hy~rocarbon solvent which is, if necessary, employed in method tA), is selected, mainly depending upon ~
the type of ether employed. Specific axamples of the hydrocarbon ;
include to saturated aliphatic hydrocarbons such as n-pentane~ ;~
n-hexane, n-heptane, n-octane, n-dodecane, liquid paraffin, ;
etc; alicyclic hydrocarbons such as cyclohexane, methyl cyclohex-ane, etc.; and aromatic hydrocarbons such as benzene, toluene, xylene, 1,2,4-trimethyl benzene, ethyl benzene, etc. In a certain case, the hydrocarbon may be selected from halohydrocar-bons such as chlorobenzene, bromobenzene, ortho-, meta- and para-dichlorobenzene, ortho-,meta- and para-dibromobenzeneJ
ortho- and para-chlorotoluene, 2,4-dibromotoluene, para-bromoethyl benzene, l-chloronaphthalene, etc. The above-described hydro-carbons may be used in admixture, if preferred.
Particularly when an ether having the formula (2) wherein at least one of R1 and R2 represents an alkyl or alkenyl radical ha~ing less than 5 carbon atoms is used, the hydrocarbon may pre~erably be an alicyclic hydrocarbon and, most preferably, an aromatic hydrocarbon. In the case of an ether having th0 formula (2) wheréin Rl and R2 represent an ; 25 alkyl or alkenyl xadical having more ~han 6 carbon atoms, the . .
. . '.~' lOq3149 hydrocarbon may preferably be a saturated aliphatic hydrocarbon.
. A halohydrocarbon may preferably be selected when diethyl : . ether is used.
For the reduction to be effected in method ~A), an organo-aluminum compound ha~ing the general formula:
RnX3-n - (3~
wherein R3 represents a hydrocarbon radical having 1 - 20 carbon atoms, n is a number of the value of 1 - 3, and X repres~nts . a halogen atom, and preferably R3 represents an alkyl radical ¦ having 1 - 10 carbon atoms i~ used. ~mong these most preferred ¦ are ethyl aluminum sesquichloride, diethyl aluminum chlorlde, ¦ triethyl aluminum, tributyl aluminum, etc.
The above-described organo-aluminum compound is used ¦ for the reduction of titanium tetrachlvride so that the molar ¦ ratio of titanium tetrachloride ~o the organo-aluminum compound . ¦ may be 1 : (0.1 - 50), preferably 1 : ~0.3 - 10), when ¦ represented in terms o~ the molar ratio of titanium to R3 ~: :
¦ constituting the organo-aluminum compound (a hydrocarbon : ¦ radical, preferably an alkyl radical). Further, the amount of ~:
:20 ¦ the ether used is adjusted so that the molar ratio of the ¦ ether to titanium tetrachloride may be 1 : (0.05 - 5), preferably from 1 : ~0.25 - 2.5).
The reduction may be effected by any of the following different procedures.
~a) An organo-aluminum compound is added to a homogeneous ;, .

3~4 liquid consisting of titanium tetrachloride and an ether r or vice versa. 1~
(b) A homogeneous liquid consisting of an organo-aluminum ;~v,?
compound and an ether is added to titanium tetrachloride, or vice versa.
~c) A homogeneous liquid consisting oE an organo-aluminum compound and an ether is added to a homogeneous liquid consis-ting of titanium tetrachloride and an ether, or vice versa.
(d) Titanium tetrachloride, an ether and an organo-aluminum compound are mixed with each other in any suitable sequence at a temperature at which reduction cannot occur, for e~ample at a temperature below -30C and the mixture is then heated to a given reduction temperature.
Titanium tetrachloride, an ether and an organo-aluminum compound may be used either in the form of pure reagents or in the form of reagents diluted with an appropriate solvent in the above procedures. It is paricularly desired to dilute the organo-aluminum compound with a hydrocarbon solvent. The reduction temperature is selected from within the range of -30 to +50C, preferably 10 - ~0C.
The reduction of titanium tetrachloride with the organo-aluminum compound in the presence of the ether according to any of the above-described procedures results in a homo-geneous liquid which is a homogeneous solution or mixture consisting of titanium trichloride and the ether, besides aluminum compound :, :

iQ~3149 and unreacted titanium tetrachloride etc. in a certain case.
This solution is soluble in the hydrocarbon solvent and is brown or greenish brown.
It is also preferable that iodine or an iodide is coexistent with the ether during the reduction of titanium tetrachloride in the above-described method (A). In this case, iodine or an iodide may preferably be added before the reduction of titanium tetrachloride is effected. I~ is also ~ possible to add iodine or iodide after the reduction is commenced, so ~ar as the reduction has not substantially baen completed.
Next, the method (B) is explained below. That is~
solid titanium trichloride is used as a starting material, which is treated with an ether, if necessary, in the presence of a suitable hydrocarbon solvent, obtaining a homogeneous liquid comprising titanium trichloride. The solid ~itanium trichloride is prepared for example, by reducing titanium tetrachloride with hydrogen gas and aluminum or an organoaluminum compound. The thus obtained solid titanium trichloride may further be comminuted in a ball mill, or heat treated. In another case, the above-mentioned solid titanium trichloride ;~
may be purified by removing the impurities contained therein.
The starting material may be selected from the foregoing.
The ether which is used to obtain the homogeneous . ~;:
liquid-eomprising titanium trichloride and the hydrocarbon '~:
. .:`

~8~3149 solvent which is optionally used in the method (B) include :
the same groups of compounds as described in the method (A)~
respectively.
l The amount of ether used in the method (B) is adjusted so that the molar ratio of ether to titanium trichloride may , be above 1/l, preferably (l S)/l, most preferably (1-2~
The treatment of solid titanium trichloride with the ether may be effected by mixing them in any desired manner at a temperature of -30 to +120C, preferably lO - 50C. ~. -Generally, such a treatment is effected in the presence of a hydrocarbon solvent which may be selected dependeing : upon the type of the ether used as described above with respect to the method (A). It is howe~er, preferred not to use an ether in which R and R of the ~ormula (2) is alkyl group `
having more than 6 carbon atoms. It is to be noted that . homogeneous liquids obtained by the method (B) are Qquivalent I to those by the method (A).
As apparent from the above explanations, the homo- :
geneous liquid comprising titanium trichloride can advantageously be prepared by the above method (A) or (B).
In a subsequent stsp, fine granular titanium trichloride having a high catalytic activity to olefin poly-~erization is precipitated in the presence of a Lewis acid from the homogeneous titanium trichloride-ether liquid.

1~1~3149 ¦ The precipitation is not limited to any ¦ particular method, but can be performed according to any of ¦ widely varying methods. For example the above-prepared homo- ~:
¦ geneous liquid as such or, if desired, after aaded with the ¦ above-mentioned hydrocarbon diluent, i~ heated in the presence of a Lewis acid to a temperature of usually from 20 - 150C, preferably from 40 - 120C, most prefe;rably from 60 - 100C to induce the precipitation, and then maintained at thle same temperature for a certain period of time to ensure the precipi-tation until completion.
~n this case, in order to facilitate the precipitation,~
the amount of aforementioned hydrocarbon solvent is preferred to:
be not less than twice by weight of the ether~
In a certain case where the total mole number of titanium and aluminum is less than the mole number of the ether in the homogeneous liquid comprising titanium trichloxide, an additional Lewis acid may preferably be added to as~ist precipitation. : ::
As the ~ewis acid used for the above purpose, mention may be made of Lewis acids having stronger acidity than titanium trichloride, for example, organo-aluminum compounas having the general formula:
AQRn'X3-n~ (4) wherein R represents an alkyl radical having 1 - 8 carbon atoms, n' is a number of 0, 1, 1.5 or 2, and X represents a halogen 0~3i49 atom, titanium tetrachloride, boron trifluoride, boron trichloride, antimony pentachloride, gallium trichloride, ferric trichloride, tellurium dichloride, stannic tetràchloride, vanadium tetrachloride, thallium pentachloride, zirconium tetrachloride, beryllium dichloride, and the corresponding ;~
bromides and hydroxyhalides. Among them most preferred are organo-aluminum compounds of the general formula (4) and titanium tetrachloride. ;
l'he amount of the hewis acid to be added may preferably be less than 5 moles per mole of the titanium in .
the homogeneous liquid. Such an amount of the Lewis acid i~ :
added to the homogeneous li~uid beore the precipitation is completed.
The precipitation may be effected in multi-steps of different temperatures. For example, a small portion is precipitated at a relatively low temperature and then the tempexature is raised to cause a major portion to precipitate :
in the presence of the small portion of previously precipitated fine-granular solid titanium trichloride. More illustratively, first of all, the homogeneous liquid is heated to a relatively low temperature of 20 - 70C to precipitate 1 - 50 wt% of ;
the total theoretical precipitation amount of finer-granular solid purple titanium trichloride, and then the temperature ;:
is raised to an elevated temperature of 45 - 150C to precipitate ~:
25. the remaining portion of fine-granular solid purple titanium ;

~ 3i49 trichloride.
A seeding procedure may also be recommended with respect to the precipitation, in which fine-granular solid titanium trichloride, for example, having an average particle diameter of 0.01 ~ 50 ~ is previously added as seed crystals to the homogeneous liquid comprising titanium trichloride before the precipitation is commenced. The kind of solid titanitum trî-chloride added as seed crystals is not particularly restricted.
Any of titanium trichloride catalysts prepared by the conven- ;
tional methods may be employed, while fine-granular solid titanium trichloride prepared by precipitating from the homogene-ous liquid comprising titanium trichloride acccrding to the above-described method is preferable. The amount of solid titanium trichloride to be added is, for example, 0.005 - 50 wt~, preferably 0.01 - 25 wt% of the theoretical amo~int of solid titanium trichloride precipitated.
According to the above-described method ~A) or (B), a fine-granular solid purple precipitate of titanium trichloride is obtained. This solid titanium tr~chloride may either be ;` 20 directly used for polymerization or be pretreated with an organo-aluminum compound, an propylene monomer and/or a phosphite (to be described hereinafter) according to the conventional manner be~ore it is used for polymerization.
- The component (b), or the organo-aluminum compound of the catalyst system according to this invention includes, by way of illustration, trialkyl aluminum~ ~uch as trimethyl . '`'-' lOq3149 ~

aluminum, triethyl aluminum, triisobutyl aluminwn, trihexyl aluminum, etc.; and alkyl aluminum halides such as dimethyl aluminum chloride, diethyl aluminum chloridel ethyl aluminum chloride, diethyl aluminum bromide, ethyl aluminum sesquichlori~e etc. A mixture of an aluminum halide and 'a trialkyl aluminum ~;
may also be employed. Among these preferr,ed are dialkyl aluminum halides and most preferred is diethyl aluminum chloride. ~ ;.i The second component (b) is mixed with the first component (a) so that the molar ratio of Al/Ti may lie in the r range from 0.1/1 - 20~1, preferably in the range from 2/1 - 10/1.
In the catalyst systems according to the present invention, the organic phosphite having the general formula (1), P(OR)nX3 n is used as the third component (c) in addition to the above two components ~a) and (b). In the formula (1), R repre-sents a hydrocarbon radical having 1 ~o 30 carbon atoms, for example, alkyl, alkenyl, aralkyl, aryl, alkaryl and cycloalkyl radical or the like, and X represents halogen, for example, chlorine, bromine, iodine or fluorine.
Included within the scope o~ the above formula are triphenyl phosphite, trito~yl phosphite, trinonylphenyl phosphite, tristearylphenyl phosphite, nonylphenyl diphenyl phosphite, decyl dlphenyl phosphite, trioctyl phosphite, dilauryl chlorophosphite, and the like. Particularly, triphenyl phosphite ~eries compounds having the general formula:

( ~ ~3 P
. : :~

iO~3149 ~:

wherein R5 denotes hydrogen or alkyl or alkenyl radical having l to 20 carbon atoms, are preferred. The proportion o the third component ~c) in the catalyst system is adjusted so that the molar ratio of organic phosphite to TiCl3 may lie in the range from 0.01 - l, preferably in the range from 0.05 - 0.2.
The catalyst system of the present invention is prepared from the above three components, to which prepartion any conven-tional method may be applied. For example, the above three com-ponents may previously be mixed in a solvent which is to be used as a polymerization medium. Conditions under which catalyst~
are prepared, including temperature, atmosphere~ and solvent, 1 are not particularly limited. However, if reaction is undertaken ; immediately after the catalyst is prepared, it is, of course, pre~erred to use preparation conditions equal to polymeriæation conditions. Further, even when the catalyst is prepared in advan~ e; `~
it is preferred to apply conditions similar to those for polymerization. However, it îs also possible to mix the three components at temperatures near room temperature using a partial -~ or entire volume of the solvent to be used in polymerization.
; 20 According to the process of the present invention~
polymerization of propylene is carried out in the presence of the thus prepared catalyst system. ~;
In the polymerization procedure, conventional slurry or gas phase polymerization may be applied. Polymerization may be carried out either continuously or in a batch manner under a pressure of 1 - 15n abmr, preferably 5 - 30 atm. at a ~ ;
,' . , ' ~ - 16 -1~3~4~

temperature of 50 - 100C, preferably 55 - 70C~ ~n the case of slurry polymerization, hydrocarbon solvents such as hexane, heptane, cyclohexane, benzene, toluene, pentane, butane, propane, etc. may be used as a polymerization medium~ while propylene .
itself may also be utilized as a medium. The polymer product obtained by slurry or gas phase polymerization may be treated in an alcohol and a hydrocarbon solvent in order to remove the residue of the catalyst without making the present process less advantageous. Further, in order to modify the molecular weight of produced polymers, a modifying amount of well^-known molecular weight modifiers such as hydrogen, diethyl ;
æinc, and the like can be added during polymerization.
The process of the present invention as described above can attain the following outstanding efects.
(l) Catalytic efficiency is very highO The catalytic efficiency CE (gram number of po~ypropylene produced per gram of the TiCl3 catalyst component) is generally above 5,000 and can be easily increased to above 10,000 under optlmum conditions. Therefore, removal of a part of the catalyst remaining in $he polymer may be omitted or simplifiecl. On the contrary, it is almost impossible to obtain a CE value of more than 3,000 in the case of the conventional catalyst systems of titanium trichloride and organoaluminum compounds.

(2) As obvious from Examples described hereinafter, polymerization activity is several times higher as compared with the conventional catalyst systems of titanium trichloride. ;

(3) The stereoregurality of the! produced polymers is extremely high. Isotactic index II (represented in terms of percent by weight as a residual quantity let after extraction with boiling n-heptane) is generally ' above 93 ~ and can be easily increased to above 96 %
under optimum conditions. The polymer products may be used practically for molding or fabrication purpose without an after-treatment to remove amorphous polymers as reguired in the con~antional case. That is, the polymer products exhibit sufficiently improved tensile impact strength and yield strength withou~ removal of amorphous polymers. As a result, the unit of propylene monomer is outstandingly improved. ;

(4) Since a slight amount of amoxphous polymers is only produced, the polymerization liquid is not increas-ed in viscosity when a solvent is used during polymeri-zation. In other words, since the polymer foxmed does ;
not adhere to the wall of a reactor or other equipment nor the polymer paricles formed coalesce into one mass, operations are very easy.
Further, amorphous polymers foxmed in the process of the present invention seem to be different from those . . '' ;'' ~ :: :

contained in polymer products formed according to the conventional method. According to the process of the present invention, the amorphous polymer remaxkably decreases its solubility in hydrocarbon sol~ents, as temperature decreases. This means that stable operations are ensurea during polymerization, after-trea~ment, and other steps. The above phenomenon is made more outstanding in the presence of the organic phosphite as the third catalyst component. On the contrary, the pxesence of triphenyl phosphite has no influence on the solubility of amorphous polymers in the case of the conventional catalyst systems.
; (5) In addition, other merits are ascertained in that the polymers formed according to the process of the invention have a high bulk density and that the polymers formed by slurry polymerization exhibit a narrow particl~ ~`
size distribution.
As obvious from the abo~e, not only polymerization activity and catalytic efficiency are increased, but stereo~
regularity is also remarkably improved according to the process of the invention. Such simultaneous improvements cannot be ach~eved by the prior known processes and therefore, it can be said that the process of the invention is of industrial significance. ;

l The following examples illustrate the invention. They ¦ are set forth as a ~urther description, hut are not to be I construed as limitin~ the invention thereto. In t~e examples ¦ and comparative examples, the abbreviations stand for the ¦ following meansings.
i) K : polymerization activity represented in terms of the ~nount (g) of polypropylene produced per gram of the -~catalyst-constituting titanium trichloride component l per hour at an olefin-charge pressure of l kgjcm2. ;~
O 1 ii) CE : catalytic e~ficiency represented in terms of the amount (g) of polypropylene produced per gram of the catalyst-constituting titanium trichloride component.
iii)I.I. : isotactic index represented in terms of the amount ~wt%) of the polymer remained after a 6-hour~
extraction with boiling n-heptane in a modified- ~ ;
type Soxhlet apparatus. Since the amorphous polymer which causes physical pxoperties to decrease is soluble in boiling n-heptane, I.I. shows the yield of the crystalline polymer.
iv) PB: bulk density (g/cc~ measured according to JIS 6721.
v) MFI : melt flow index (g/10 min.) measured according to ASTM D-1238.
vi) YS : strength at primary yield point (kg/cm2) measured according to ASTM D-412.
. , ..

~ 20 - !

10~3i4 vii) TI : tensile impact strength ~kg-cm/cm2) measured according to ASTM D-1822 viii) Particle size distribution of the polymer The particle size is measured by the screen classifi- ;
S cation method and the resulting values are plotted in a Rosin-Rammler paper to draw a graph. With reference to the detail of dra~wing, see "Kagaku Kogaku Binran", pp 36l-362, Maruzen K~K, (May lO, 1968). It is to be noted that DpO represents a particle size ~ ~ ) at which a 50 wt% portion of the entire poIymer granules is screened out~
Example l:
A~ Pre~aration of titanium trichloride A l-liter four-necked flask is charged with 300 ml of n-heptane, 180 mmols of titanium tetrachloride and 180 mmols `~
of n-octyl ether at room temperature. A homogeneous, amber solution is obtained. With stirring 60 mmols of diethyl aluminum -monochloride is then added. A homogeneous, dark-brown solution is obtained immediately after addition. Thereater, the solution is heated up to ~0C using an oil bath. In the course of ~
temperature rise, a purple precipitate is observed at a ;
temperature of about 60C. The solution is maintained at 90C ;~
for 1 hour. Stirring is stopped and the resulting granular purple precipitate of titanium trichloride is separated and then washed with n~heptane. This titanium trichloride is used as a first component of a catalyst system.
l : , ~ 3~4 B. Polymerization of propy_ene ..
An autoclave through which purified propylene gas flows is charged with 1 Q of purified n-hexane and then 23.1 mg of titanium trichloride prepared in the abo~e. Thereafter, ~;
72 mg of diethyl aluminum chl~ride ~to be referred to as "DEA", hereinafter) is added as a second component so that the molar ratio of AlTi is 4 and then triphenyl phosphite (to be referred to as "TPP", hereinafter) as a third component so that the molar ratio of TPP to TiC13 i~ 0.10. With stirring the ; ;
temperature in the autoclave is raised to 69C. Thereafter, 0.50 kg/cm2 of hydrog~n gas and 20 kg/cm2 of propylene monomer are charged. Polymerization is conducted for 5 hours. The contents including the solvent in the autoclave is taken out in a stainless steel vat. Upon drying, 336 g of a polypropylene (propylene homopolymer) containing all the amorphous polymer is obtained in a white powder form. The results are as follows.
CE K PB II Dp 14,545- 145 0.46 96.4 320~ ' . .~ ~
The particle size distribution is given by the line connecting circles, in Fig. 1.
Comparative Example 1:
Polymerization is conducted following the procedure of Example 1 except that TPP as the third component of the catalyst system is not used. While powdery polypropylene con-taining all the amorphous polymer weights 342 g. Ths results are as follows.
CE K PB II Dp 14,805- 148 0~41 88.6 330 31~9 Comparative Example 2:
In this example, a commercially available titanium trichloride catalyst is used (TiC13 1/3Al(~13, manufactured and sold under the trade mark.l'TAC 141" by Toho Titanium Co.).
A 2-liter autoclave through which propylene gas ~lows is :
charged with 1 Q of n-hexane, 113 mg of TAC 141, DEA in an .
amount to give a molar ratio of Al/Ti of 4, and TPP in ~n ~:
amount to give a molar ratio of P/Ti of 0~1 in this order. The .
subse~uent operations are identical wi h those described in Example 1. All the contents including the solvent in the ;~
autoclave is taken out and dried, obtaining white powdery : ~:
polypropylene containing all the amorphous polymer. The results are as follows.
CE K PB II Dp .
2,66~ 26.6 0.38 94.8 370~ ~ -The particle size distribution is given by the line connecting :~
triangles, in Fig. 1. As apparent from the graph of Fig. 1, particle diameters of polypropylene particles produced in Example 1 according to the process of the invention fall within a narrower range than those in Comparative Example 2. Accordiny-ly, the process of the invention i5 effective even in particle size distribution.
E _ ~les 2 - 4 and Comparative Examples 3 - 5~
Polymerization is conducted according to the procedures described in Example 1 and Comparative Example 2, respecti~ely, ::

:~ ~ 3~9 :':

while the amount of TPP as the third component is varied as shown in Table 1. The results are shown in Table 1. All the data refer to polymers containing all the amorphous polymer.
' In Table 1, the data concerning pol~mers in Example 1 and ;
: 5 Comparative Examples 1 and 2 are also incorporated for the sake of comparison.

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1Oq314 Asapparent from Table 1~ the process of the invention .
is considerably advantageous in that the stereoregularity is improved and the polymerization activity and catalytic efficiency are very high in comparison with the cases using the con~entional ~
titanium trichloride catalyst. :~ :
Comparative Example 1 shows that, if the third `~
component of the catalyst is eliminated, the use of the particu~
lar titanium trichlorîde only provides the product with a poor -stereoregularity. Such a product cannot be used in practice.
without an after-treatment to remove the amorphous polymer. ..
. , ~: ' '' ';
.
. A 1-liter four-necked flask is charged with 300 ml of toluene. With stirring at room tempera~ure 180 mmols of titanium tetrachloride and 180 mmols of n-butyl ether are added to toluene to obtain a homogeneous, dark-bro~n solution. :-.
i With stirring 90 mmols of diethyl aluminum monochloride is further added. Thereafter, the temperature is increased up :.
to 90C and maintained thPre for l hour. In the course of temperature rise, a purple precipitate of titanium trichloride ~ ;~
is observed at a temperature of a~out 50C. ~he solution is maintained at 90C for l hour. The resulting granular purple precipitate of titani~m trichloride is separated and then washed with toluene, obtaining a titanium trîchloride catalyst. ..
Next, polymerization is conducted in the ~ame manner as described in Example 1~ In this example, 22.$ mg of the . ~ ~

i~73149 above-prepared titanium trichloride catalyst is used and DEA
in an amount to give a molar ratio of Al/Ti of 4 and TPP as the third component in an amount to give a molar ratio of TPP/Ti of 0.15 are added. All the contents in the autoclave is taken out in a vat and then dried, obtaining 371 g of white powdery polypropylene containing all the amorphous polymer.
The results are as ~ollo~s.
CE K PB II
16,272- 163 . 0.38 97.4 :~

Further, each product of polypropylene in the abo~e-. described Examples and Comparative Examples is tested for analys~s. The results are shown :
in table 2. It is to be noted that :
the products of Examples 1, 2, 4 and `

5 are obtained according ¦ to the process o the invention, the product of Comparative Example 1 is obtained in the presence of a ca~alyst system which contains the particular titanium trichloride according ¦ to the invention, but not TPP as the third component, and the .
products of Comparative Examples 2 and 4 are obtained in the presence of catalysts which contain the conventional titanium trichloride catalyst, TAC-141, DEA as the second component and TPP as the third component. Each polymer product, is subjected ; to after-treatment o thoroughly washing with methanol, water and hydrochloric acid to deactivate and remove the catalyst . .
:~

10~31~19 1 ;
.. ~:

completely. This after~treatment does not remove the amorphous polymer. Therefore, each polymer to ~e tested contains all the amorphous polymer.
Table 2 II MFI YS TI
Example 1 96.4 4.7 348 62 Example 2 96.B 608 357 65 :~
Example 4 97~2 7.3 351 61 Example 5 97.4 S.7 355 63 Comparat ve 88.6 5.8 303 58 Comparative 94 8 6.4 331 54 Example 2 Comparative 95 0 7 7 329 52 Example 4 ,~

It is obvious from Table 2 that the polymer pxoducts a~cording to the invention are also excellent with respe~t to the above-tabulated physical properties.
I ~xamples 6 - 8~
In these examples, polymerization is conducted accord-ing to the process of the invention using different phosphorus compounds as th~ third component. The procedures described in Example l~B are followed except that phosphorus compounds as shown in Table 3 are used instead of TPP. Physical properties of the polymer produots (containing the amorphous polymer) and effects of the catalysts are shown in Table 3.
- `' lOq3149 l ~ ~ x ~
.

~,~ t ~ o o oj~3 ~ ~ ~

I
I l- ~ ~ ~ .
l ~ ~ :-I ~ D ~ ~

~ ~ ~ O o ~ ¦ ~
~ ul a. u ,~

-29- ~ ~

~ lOq3149 ¦ Example 9 ana ComparatiVe Example 6;
l ~ .
¦ In these examples~ the polymerization of propylene is ¦ conducted in the absence of a solvent.
; ¦ In Example 9, 24.0 mg of the titanium trichloride ¦ catalyst as described in Example l~A, is charged and DEA in I an amount to give a molar ratio of DEA/TiC13 of 6,0 and TPP a ; ¦ molar ratio of TPP/TiC13 of 0.1 are added. ~hereafter, hydrogen . gas is fed up to a.partial pressure of 0.2 kg/cm~ and 1~5 Q
of liquified propylene is charged. Polymerization is ,conducted at 60C for 4 hours. Thereafter, the remaining propylene mono-. mer is purged and the contents are dried, obtaining poly-.; propylene.
In Comparative Example 6, 95.0 mg o the conventional titanium trichloride catalyst, TAC~141~ is charged and DEA .
in an amount to give a molar ratio of DEA/TiC13 o~ 2.0 and TPP - :
a molar ratio of TPP/TiC13 of 0.1 are added. The remaining :~
conditions and operations are iden~ical with those described in Example 9. Physical properties of each polypropylene product containing all the amorphous pol~mer as well as effacts of the catalysts are shown in Table 4.
Table 4 CE K II P~ MFI YS TI
Example 9 11,310 113 96.6 0.41 4.6 349 61 Co~pa at6ive 2,730 27.3 93.2 0.37 5.3 321 54 . . '~
. ' . , Example 10:
This example aims to show that a pol~mer pro~uct obtained according to the invention, though containing all the amorphous polymer ormed in an accompcmying manner~ shows satisfactory physical properties which are comparable to those of a purified polymer product from which a part of the amorphous polymer has been removed. .
First of all, a polymex product containing all the amorphous polymer is obtained in the same manner as described in Example 1 B. The physical properties of the product and effects of the catalyst are as follows.
CE K II PB MEI YS TI
14,390 143- 96.7 0.44 4.6- 3~9 ~1 -:-Next, the above produc~ is subjected to extraction with n-hexane at 70C. ~y this extraction, 1.3 wt% of the amorphous polymer is removed. The results are as follow~.
II MFI YS TI - ~
98.0 5.0 353 60 ~ .

Comparati~e_Example 7:
This example corresponds to Example 10. Polymerization is conducted in the same manner as described in Comparative ~-Example 2. Physical properties of a polymer product which is ~.
obtained ater the polymerization and contains all the amorphous polymer and a purified product ~ro~ which a major part of the amorphous polymer has been xemoved by extracting with n-hexane . :,.' 10~3149 at 70C, and effects of the catalyst are determined. :
Before extraction:
CE K II PB MFI YS TI
2,593 25.9 94.3 0.39 5,3 ~ 54 ;
After extraction:
the amount of the amorphous polymer removed = 4.9 wt~
II MFI YS TI :
99 5.8 355 53 .
. `:~ .
The comparison of the results of Example 10 w:ith those of Comparative Example 7 shows that the conventional process ~:~
needs the after-treatment to remove the amorphous polymer after the polymerization, while the process of the invention can provide a polymer product with physical properties satisfactory ~or pr: tical appllaatlon without such an after-treatment.

: .
~ ~
, ~ ' ' . ~'', .

Claims (15)

WHAT IS CLAIMED IS:

1. In a process for the polymerization of propylene in the presence of a catalyst system comprising (a) titanium trichloride, (b) an organoaluminum compound and (c) an organic phosphite having a formula: P(OR)nX3-n (wherein R denotes a hydrocarbon radical having 1 - 30 carbon atoms, X a halogen atom, and n a number of 1 - 3), an improvement which comprises using as said titanium trichloride, a finely granulated purple solid obtained by precipitation from a homogeneous liquid mixture or solution of titanium trichloride and an ether in the presence of a Lewis acid.

2. The process according to claim 1 wherein the titanium trichloride is a finely granulated purple solid obtained by precipitation from a homogeneous liquid mixture or solution of titanium trichloride and an ether in the presence of a Lewis acid and a hydrocarbon solvent at a temperature in the range of 20 - 150°C.

3. The process according to claim 2, wherein R denotes a hydrocarbon radical having a formula (wherein R denotes a hydrogen atom, or an alkyl or alkenyl radical having 1 - 20 carbon atoms).

4. The process according to claim 2, wherein said phosphite is triphenyl phosphite, tristearyl phosphite, tributyl phosphite, trinonylphenyl phosphite or monochloro didodecyl phosphite.

5. The process according to claim 2, wherein a molar ratio of (a) titanium trichloride to (b) an organo-aluminum compound to (c) an organic phosphite is within the range of 1 :(0.1-20):(0.01-1).

6. The process according to claim 2, wherein said ether has a formula: R1-O-R2 and R1 and R2 are individually selected from the group consisting of alkyl and alkenyl radicals;
and wherein said hydrocarbon solvent is selected from the group consisting of saturated aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and their halogenated derivatives.

7. The process according to claim 6, wherein said R1 and R2 respectively have at least six carbon atoms; and where-in said hydrocarbon solvent is a saturated aliphatic hydrocarbon.

8. The process according to claim 2, wherein at least one of said R1 and R2 have five or less carbon atoms; and wherein said hydrocarbon solvent is an aromatic or alicyclic hydrocarbon.

9. The process according to Claim 2, wherein said Lewis acid is titanium tetrachloride.

10. The process according to Claim 2, wherein said temperature is within the range of 40 - 120°C.

11. The process according to Claim 2, wherein said heating is conducted in at least two separate stages.

12. The process according to claim 2, wherein said homogeneous liquid is prepared by reducing titanium tetrachloride with an organoaluminum compound in the presence of an ether and a hydrocarbon solvent.

13. The process according to claim 12, wherein the molar ratio of said ether to titanium tetrachloride is within the range of 1 : (0.05-5).

14. The process according to claim 2, wherein said homogeneous liquid is prepared by mixing solid titanium tri-chloride with a dialkyl ether in which each alkyl radical has six or more carbon atoms and wherein said hydrocarbon solvent is a saturated aliphatic hydrocarbon.

15. The process according to claim 14 , wherein the molar ratio of said ether to titanium trichloride is within the range of 1-5.