Alpha-olefin block copolymer particles and process for the production thereof

A process for the production of .alpha.-olefin block copolymer particles having excellent impact resistance at low temperature and excellent molding and processing characteristics, is disclosed. The process includes a two step gas phase polymerization procedure under specific conditions in the presence of a specific catalyst system.

The present invention relates to .alpha.-olefin block copolymer particles 
which are produced by so-called gas phase polymerization where gaseous 
.alpha.-olefins are directly converted into polymer. More particularly, 
the present invention relates to .alpha.-olefin block copolymer particles 
having excellent impact resistance at low temperature and excellent 
molding and processing characteristics, and a process for the production 
thereof by polymerizing .alpha.-olefins by two steps under specific 
conditions in the presence of a specific catalyst system. 
BACKGROUND OF THE INVENTION 
Since a catalyst for producing stereoregular polymers had been discovered 
by Ziegler, Natta et al., crystalline .alpha.-olefin polymers have been 
produced on an industrial scale. Among the conventional processess for the 
industrial production of the polymers, a slurry polymerization process has 
the most widely been used, wherein an .alpha.-olefin(s) is(are) 
polymerized in an inert liquid solvent. 
However, the slurry polymerization process has some drawbacks. For 
instance, the produced polymer is separated from the solvent and then 
dried. The separated solvent contains low-crystalline polymers dissolved 
therein, and hence, in order to re-use the solvent, the dissolved polymers 
must be removed therefrom. That is, after the removal of the 
low-crystalline polymers, the solvent is purified and then re-used. Thus, 
this process requires a complicated procedure and a large amount of energy 
for the removal of low-crystalline polymers. Moreover, when a polymer 
containing a large amount of low-crystalline polymers is produced by the 
process, the low-crystalline polymers are dissolved in the solvent in a 
large amount, which causes an increase in the viscosity of the 
polymerization system. In such a case, it is difficult to remove the heat 
of polymerization, and further, due to adhesion of the polymer particles 
onto the polymerization vessel, the desired polymer is hard to obtain. To 
avoid such drawbacks in the slurry polymerization, it has been proposed to 
polymerize .alpha.-olefin(s) in the gaseous phase in the absence of an 
inert liquid solvent, but such a gas phase polymerization process still 
has some problems to be solved to produce a block copolymer having 
improved impact resistance at low temperatures and improved molding and 
processsing characteristics. 
One of the most important problems in the gas phase polymerization process 
is that the production of a polymer containing a large amount of 
low-crystalline polymers, such as a block copolymer having excellent 
impact resistance, the polymer particles usually adhere easily onto the 
polymerization vessel and hence it is difficult to obtain the desired 
polymer in a stable manner. To eliminate this effect, it is necessary to 
lower the adhesion properties of the polymer particles. 
As a reaction vessel for the gas phase polymerization of .alpha.-olefin(s), 
there are used an agitating mixing type vessel, a fluidized bed type 
vessel, an agitating fluidized bed type vessel, and the like. However, 
with an increase of adhesion of the polymer particles, an extremely large 
force for agitation is required to obtain the desired rotation of the 
agitator, which causes difficulty in the design of the apparatus. In 
addition, an occasionally difficulty in the homogeneous mixing of the 
reaction mixture arises and some portions reach too high of a temperature, 
which results in the production of a partial chunk injuring the agitator, 
thermometer, etc. within the reaction vessel or resulting in difficulty in 
removing the polymer through a pipe from the vessel. 
Moreover, in polymerization in the fluidized bed, a slugging phenomenon 
tends to occur, and hence, a large amount of the polymer particles fly 
into the gas circulation line and adhere onto the line, which results in 
closing of the line. There is also occasionally produced undesirable 
partial chunks due to the difficulty in homogeneous mixing. In the 
production of polymer particles having high adhesion properties, the pipe 
for transferring the polymer particles is easily closed. Furthermore, 
undesirable bridging occurs at the lower part of a cyclone or within the 
hopper, and hence, the polymer cannot be removed in a stable manner. 
Accordingly, it is very difficult to produce a polymer containing a large 
amount of low-crystalline polymer by a gas phase polymerization process, 
so that the process has an advantage in that there is not liquid solvent 
dissolving the low-crystalline polymer. 
Another important problem in the gas phase polymerization process is that 
it is necessary to prevent a wide range of particle size distribution. 
That is, according to the conventional gas phase polymerization process, 
to homogeneously mix the reaction mixture and to remove easily the heat of 
polymerization, a part of the gaseous components is usually drawn out from 
the top of the reaction vessel and cooled to remove partially or wholly 
the heat of polymerization and then returned to the reaction vessel. In a 
typical process where gas components are circulated, there is used a 
fluidized bed type vessel or an agitating fluidized bed type vessel, 
wherein a part or whole of the gas is circulated, and thereby, the power 
necessary for agitation can be saved and the mixture can homogeneously be 
mixed so as to result in easy removal of the heat of polymerization. 
However, when the polymerization is carried out by using a catalyst system 
containing a large amount of fine particles within a reaction vessel 
wherein the gas components are circulated, the fine particles of the 
catalyst and also the polymer particles fly within the vessel, which 
causes some troubles in operation. For instance, the fine particles are 
accompanied with the gas to be exhausted from the reaction vessel into the 
circulation line and adhere onto the pipes and devices provided in the 
line, such as the cyclone, filter, heat exchanger, compressor, flowmeter, 
and the like, and hence, the devices significantly lose their capacity and 
occasionally become inoperative due to the closing thereof. Moreover, the 
fine particles fly to the dilute phase of the polymer within the reaction 
vessel and adhere onto devices provided therein, such as thermometer. In 
this phase, the polymerization reaction proceeds to produce chunks which 
cause pipes to close. With an increase in the chunks, a homogeneous 
fluidized bed is hard to obtain, which results in a difficult removal of 
the heat of polymerization and yet a further increase in the amount of 
chunks. When using an agitating reaction vessel, the agitator as well as 
other devices, such as a thermometer, are injured by the produced chunks. 
When there is used a solid catalyst which contains components having a 
large particle size, the catalyst particles flow insufficiently within the 
fluidized bed type reaction vessel, which results in incomplete removal of 
the heat of polymerization and hence the production of undesirable chunks 
increases. 
There has also proposed an improved gas phase polymerization process. In 
this improved process, the catalyst residue and atactic polypropylene 
having undesirable physical properties are not substantially removed, and 
hence, a specific catalyst system must be used which has highly improved 
stereoregular properties and polymerization activity. 
In addition to the problems during the polymerization process as mentioned 
above, the obtained polymer particles having high adhesion properties or 
containing a large amount of fine particles have some disadvantages in the 
molding and processing steps as mentioned below. 
Polypropylene is usually processed into shaped products having various 
shapes suitable for each desired application, wherein the starting 
polypropylene is made molten by heating and then molded into the desired 
shape in a film molding machine, an injection molding machine, or the 
like. The starting polypropylene is usually used in the form of pellets 
which are prepared by admixing the polymer particles with conventional 
additives such as neutralizing agents, heat stabilizers, antioxidants, 
UV-absorbers, light stabilizers, etc. and melting by heating in an 
extruder and then molding into pellets. This step of molding into pellets 
requires a large amount of apparatus and also a large power and energy for 
heating and extruding. 
To eliminate these problems, it has also proposed to directly mold the 
polypropylene particles admixed with additives without preforming into 
pellets. However, the direct molding of the polymer particles still has 
some problems and has rarely been employed practically. One of the main 
problems is that the particles are not suitable for adaptation to the 
molding machine, that is, the particles are insufficiently separated at 
the cyclone of the hopper loader provided in the molding machine and fly 
into atmosphere. Additionally, when polymer particles having high adhesion 
properties are molded, the particles adhere onto and close various devices 
provided in the molding machine, such as pipes for transferring, hoppers, 
cyclones, etc., by bridging. Thus, it has been desired to improve the 
properties of the polymer particles for the purpose of molding and 
processing thereof. 
SUMMARY OF THE INVENTION 
The present inventors have extensively studied an improvement in the 
production of .alpha.-olefin block copolymers having excellent properties 
and have found that the desired polymer can be produced by polymerizing 
.alpha.-olefins in two steps under specific conditions in the presence of 
a specific catalyst system. 
Accordingly, object of the invention is to provide an improved gas phase 
polymerization process wherein gaseous .alpha.-olefins are directly 
converted into a polymer. 
Another object of the present invention is to provide a process for the 
production of .alpha.-olefin block copolymer particles having excellent 
impact resistance at low temperatures and excellent molding and processing 
characteristics. 
A further object of the present invention is to provide a process for the 
production of the desired copolymer particles as described above in a 
stable manner on industrial scale. 
These and other objects and advantages of the invention will be apparent to 
those skilled in the art from the following description.

DETAILED DESCRIPTION OF THE INVENTION 
The process for the production of .alpha.-olefin block copolymer particles 
of the invention comprises 
(1) a first step comprising homopolymerizing propylene or copolymerizing 
propylene with a comonomer of ethylene or an .alpha.-olefin having 4 to 6 
carbon atoms so that the content of the comonomer to be copolymerized in 
the copolymer produced in this step becomes in the range of not more than 
6% by mole, and further that the polymer produced in this step shares 90 
to 30% by weight based on the whole weight of the polymer, the 
polymerization being carried out in liquefied propylene or in a gaseous 
phase, 
(2) a second step comprising homopolymerizing ethylene or copolymerizing 
ethylene, propylene and an .alpha.-olefin having 4 to 6 carbon atoms or a 
mixture thereof so that the ethylene content in the copolymerization 
product produced in this step becomes in the range of not less than 10% by 
mole and further that the polymer produced in this step shares 10 to 70% 
by weight based on the whole weight of the polymer, the polymerization in 
the first and second steps being carried out in the presence of a catalyst 
system comprising 
(A) a solid catalyst component containing at least titanium, chlorine and 
an electron-donating compound and having a pore volume of not less than 
0.08 cc/g in the range of a pore radius of 200 to 15,000 .ANG., a mean 
particle size of 5 to 100 .mu.m, and a geometric standard deviation 
(.sigma.g) of the particle distribution is not more than 2, and 
(B) an organic aluminum compound. 
The .alpha.-olefin block copolymer particles of the invention comprise (a) 
a first segment consisting essentially of propylene alone or a combination 
of propylene and not more than 6% by mole a comonomer of ethylene or an 
.alpha.-olefin having 4 to 6 carbon atoms; (b) a second segment consisting 
essentially of ethylene alone or a combination of ethylene, not more than 
90% by mole of propylene and an .alpha.-olefin having 4 to 6 carbon atoms 
or a mixture thereof; the second segment being contained in a ratio of 10 
to 70% by weight based on the whole weight of the copolymer; and have a 
mean particle size of 150 to 3,000 .mu.m, a geometric standard deviation 
(.sigma.g) of the particle distribution of not more than 2, and an 
adhesion force of not more than 6.0 g/cm.sup.2. 
The catalyst system used in the present invention is illustrated in more 
detail below. 
(A) Solid catalyst component: 
The solid catalyst component used in this invention contains at least 
titanium, chlorine and an electron-donating compound and has a pore volume 
of not less than 0.08 cc/g in the range of a pore radius of 200 to 15,000 
.ANG., a mean particle size of 5 to 100 .mu.m, and a geometric standard 
deviation (.sigma.g) of the particle distribution of not more than 2. 
According to the extensive study by the present inventors, it has been 
found that the adhesion force of the polymer particles has a close 
relationship with the pore volume in a limited range of a pore radius of 
the solid catalyst component. 
It has already been proposed to decrease the particle size of the primary 
particles in the solid catalyst component and thereby to increase the 
specific surface area thereof (cf. U.S. Pat. No. 4,210,738). As a result 
of the present inventors' experiments, it has been found that when the 
particle size of the primary particles is reduced, the pore volume in the 
range of a pore radius of not more than 200 .ANG. is usually increased, 
but it does not correspond to the adhesion force of the block copolymer. 
Moreover, according to the experiments on the relationship of the adhesion 
force and the pore size and pore volume, it has been found that the pore 
volume in the range of a pore radius of 200 to 15,000 .ANG. has a close 
relationship with the adhesion force. It is assumed that when a pore 
volume in the range of a pore radius of 200 to 15,000 .ANG. is larger, the 
primary particles associate and roughly coagulate to form secondary or 
higher degree coagulated particles. 
The solid catalyst component used in this invention has a pore volume in 
the range of a pore radius of 200 to 15,000 .ANG. (hereinafter shown by a 
sign: ".DELTA.Vp") and is not less than 0.08 cc/g, preferably not less 
than 0.1 cc/g, more preferably not less than 0.15 cc/g. 
It has also been found that the particle distribution of the polymer 
particles has a close relationship to the particle distribution of the 
solid catalyst component. 
Thus, the problems due to the variation of the particle size of the polymer 
particles will be solved by using a specific catalyst component having a 
specific particle distribution. 
That is, the solid catalyst component used in the invention has a mean 
particle size of 5 to 100 .mu.m, preferably 10 to 75 .mu.m, more 
preferably 15 to 50 .mu.m, and a geometric standard deviation (.sigma.g) 
of the particle distribution is not more than 2.0, preferably not more 
than 1.8. When the mean particle size is smaller than the above range, the 
polymer particles have a larger adhesion force and induce problems such as 
flying of the catalyst and polymer particles within the fluidized bed type 
reaction vessel. On the other hand, when the mean particle size is larger 
than the above range, the minimum flow rate in the fluidized bed type 
reaction vessel increases significantly and thereby it becomes very 
difficult to obtain a stable flowing state, which causes an undesirable 
production of bulky polymer particles. 
Assuming that a logarithmic probability distribution equation is applicable 
to the particle distribution, the geometric standard deviation (.sigma.g) 
of the particle distribution can be calculated by a comparison of both 
factors in the following formula, wherein Dg means a particle size in the 
case of accumulating weight % of the polymer particles being 50% by 
weight, and Dp means a particle size in the case of accumulating weight % 
of the polymer particles being 15.8% by weight: 
##EQU1## 
When the .sigma.g is larger than the above range, there is a problem of 
production of too fine polymer particles or of polymer particles having a 
larger particle size. 
By using the solid catalyst component having a specific mean particle size 
and a specific particle distribution of the present invention, there can 
advantageously be obtained the desired polymer particles having excellent 
molding and processing characteristics with less fine particles. 
The process of this invention can produce .alpha.-olefin block copolymer 
particles having a mean particle size of 150 to 3,000 .mu.m, preferably 
300 to 2,300 .mu.m, more preferably 450 to 1,500 .mu.m, and a geometric 
standard deviation (.sigma.g) of the particle distribution of not more 
than 2.0, preferably not more than 1.8. When the particle size of the 
polymer particles is less than the above range or when the polymer 
particles contain a large amount of fine particles, they have problems as 
mentioned hereinbefore. 
It has also been found by the present inventors' experiments that the 
adhesison force of the polymer particles should be not more than 6.0 
g/cm.sup.2, preferably not more than 5.0 g/cm.sup.2, more preferably not 
more than 4.0 g/cm.sup.2, and thereby, various problems due to the 
adhesion of polymer particles as mentioned hereinbefore are solved. The 
solid catalyst components used in this invention can produce the desired 
polymer particles having excellent impact resistance and a small adhesion 
force. 
Each component of the solid catalyst component is specifically illustrated 
below. 
Titanium compound is used as a main component as it exists or in the form 
of residing on an appropriate carrier. The titanium compound used in this 
invention includes chlorinated titanium compounds of the formula: 
Ti(OR.sup.1).sub.b Cl.sub.a-b wherein R.sup.1 is a hydrocarbon group 
having 1 to 20 carbon atoms, a is an integer of 3 or 4, and b is a number 
in the formula 0.ltoreq.b.ltoreq.a. The hydrocarbon group for R.sup.1 
includes, for example, a straight chain or branched chain alkyl group 
having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, 
n-butyl, isobutyl, n-amyl, isoamyl, n-hexyl, n-heptyl, n-octyl, n-decyl, 
n-dodecyl, etc.; an aryl group having 6 to 20 carbon atoms, such as 
phenyl, cresyl, xylyl, naphthyl, etc.; a cycloalkyl group having 5 to 7 
carbon atoms, such as cyclohexyl, cycloheptyl, etc.; an alkenyl group 
having 2 to 20 carbon atoms, such as propenyl, etc.; and an aralkyl group 
having 7 to 20 carbon atoms, such as benzyl, phenethyl, etc., preferably a 
straight chain alkyl group having 2 to 18 carbon atoms and an aryl group 
having 6 to 18 carbon atoms. Suitable examples of the titanium compounds 
ar titanium trichloride, mono-R.sup.1 -substituted dichlorotitaniums (e.g. 
monoalkoxydichlorotitaniums), di-R.sup.1 -substituted monochlorotitaniums 
(e.g. dialkoxy-monochlorotitaniums), titanium tetrachloride, mono-R.sup.1 
-substituted trichlorotitaniums (e.g. monoalkoxytrichlorotitaniums), 
di-R.sup.1 -substituted dichlorotitanium (e.g. dialkoxy-dichlorotitanium), 
and the like. The chlorinated titanium compounds may have two or more 
different OR.sup.1 groups. Among the chlorinated titanium compounds, 
TiCl.sub.3 is one of the most suitable transition-metal compounds. It is 
known that this titanium chloride is in the crystalline forms of .alpha. 
-, .beta.-, .gamma.-, and .delta.-type. To produce a polymer having 
streoregularity from an .alpha.-olefin having 3 or more carbon atoms, it 
is preferable to use .alpha.-, .gamma.- or .delta.-type TiCl.sub.3 having 
a layer structure. The TiCl.sub.3 contains usually 1 to 15 wt. % of an 
ether compound. The titanum compounds used in this invention also include 
the trivalent titanium halide compounds containing an alkoxy group of the 
formula: Ti(OR.sup.1).sub.b Cl.sub.3-b wherein R.sup.1 is a hydrocarbon 
group having 1 to 20 carbon atoms as defined above, and b is a number in 
the formula 0.001&lt;b&lt;0.15, which are disclosed in Japanese Patent First 
Publication No. 228504/1985 (=U.S. Ser. No. 725,499). The compounds also 
usually contain 1 to 15 wt. % of an ether compound. 
When the titanium compound is carried on a carrier, there can be used 
various carriers, such as various solid polymers, particularly a polymer 
of an .alpha.-olefin; various solid inorganic compounds, particularly 
oxides (e.g. SiO.sub.2, Al.sub.2 O.sub.3, etc.), hydroxides (e.g. 
Mg(OH)Cl, etc.), and halides (e.g. MgCl.sub.2, etc.). Preferred carriers 
are magnesium compounds, i.e. magnesium halides, magnesium oxide, 
magnesium hydroxide, magnesium hydroxyhalides. A particularly preferred 
magnesium compound is a magnesium halide (e.g. magnesium chloride, etc.). 
A preferred transition-metal compound is a halide of titanium (e.g. 
titanium tri- or tetra-chloride, phenoxytitanium trichloride, etc.). The 
catalyst component containing titanium, magnesium and chlorine components 
which are carried on a carrier as mentioned above is particularly 
preferred in this invention. 
The electron-donating compounds contained in the catalyst component (A) are 
preferably ether compounds and ester compounds. 
Suitable examples of the ether compounds are dialkyl ethers having 1 to 10 
carbon atoms in each alkyl moiety, such as diethyl ether, di-n-propyl 
ether, diisopropyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl 
ether, dineopentyl ether, di-n-hexyl ether, di-n-octyl ether, methyl 
n-butyl ether, methyl isoamyl ether, ethyl isobutyl ether, etc. Among 
these, di-n-butyl ether and diisoamyl ether are particularly preferable. 
Suitable examples of the ester compounds are lower alkyl (C.sub.1-10) or 
phenyl esters of mono- or polyvalent carboxylic acids, such as aliphatic 
carboxylic acids having 1 to 20 carbon atoms, olefin carboxylic acids 
having 1 to 20 carbon atoms, alicyclic carboxylic acids having 3 to 20 
carbon atoms, and aromatic carboxylic acids having 6 to 20 carbon atoms, 
and include specifically methyl acetate, ethyl acetate, phenyl acetate, 
methyl propionate, ethyl propionate, ethyl butyrate, ethyl valerate, 
methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl benzoate, 
butyl benzoate, methyl toluylate, ethyl toluylate, ethyl anisate, diethyl 
succinate, dibutyl succinate, diethyl malonate, dibutyl malonate, dimethyl 
maleinate, dibutyl maleinate, diethyl itaconate, dibutyl itaconate, 
monoethyl phthalate, dimetyl phthalate, methyl ethyl phthalate, diethyl 
phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl 
phthalate, diisobutyl phthalate, di-n-heptyl phthalate, di-n-octyl 
phthalate, diphenyl phthalate, and the like. 
The electron-donating compound is preferably contained in the solid 
catalyst component in an amount of 1 to 20% by weight, more preferably 3 
to 15% by weight, based on total weight of the catalyst component (A). 
The catalyst to be used in the present invention should have a high 
streorgularity and a high polymerization activity to provide well balanced 
properties to the produced block copolymer and also to obtain the desired 
product without subjecting the polymer particles produced by the 
polymerization reaction to an ash removal treatment. 
The present inventors' have found that when the polymer is produced at a 
production yield of 6,000 g or more, preferably 8,000 g or more, per 1 g 
of the solid catalyst component (A), the resulting polymer can be 
subjected to molding and processing without the necessary removal of the 
catalyst residue. When the production yield of the polymer is less than 
the above, the product after molding and processing becomes undesirably 
yellow in color or shows inferior weatherability. 
It has also been found that the above desirable feature can particularly be 
achieved by polymerizing the monomers in liquefied propylene in the 
presence of hydrogen by using the solid catalyst component (A) together 
with an organic aluminum compound (B) and optionally an electron donor (C) 
at such a production yield that polypropylene is produced in an amount of 
6,000 g or more per 1 g of the solid catalyst component (A) by reacting 
for 4 hours and further under the conditions that the polymer has a 
content of a component soluble in xylene at 20.degree. C. of not more than 
5% by weight, preferably not more than 4% by weight. 
The method for preparing the desirable solid catalyst component (A) is 
disclosed, for example, in Japanese Patent Application No. 85597/1984 
(=Japanese Patent First Publication No. 228504/1985), Japanese Patent 
First Publication No. 30407/1981, and Japanese Patent Application No. 
138471/1983 (=Japanese Patent First Publication No. 28405/1985). 
(1) In Japanese Patent Application No. 85597/1984 (Japanese Patent First 
Publication No. 228504/1985), there is disclosed the following method. 
A titanium compound of the formula: Ti(OR.sup.1).sub.n Cl.sub.4-n wherein 
R.sup.1 is a hydrocabon group having 1 to 20 carbon atoms, and n is a 
number in the formula 0&lt;n.ltoreq.4, is reduced by an organic aluminum 
compound of the formula: A1R.sup.2.sub.m Y.sub.3-m wherein R.sup.2 is a 
hydrocarbon group having 1 to 20 carbon atoms, Y is a halogen atom, and m 
is a number in the formula 1.ltoreq.m.ltoreq.3 to give a solid product 
having a hydrocarbyloxy group which is insoluble in hydrocarbon solvents. 
The solid product thus prepared is subjected to pre-polymerization with 
ethylene and then heated in the state of a slurry in the presence of an 
ether compound and titanium tetrachloride in a hydrocarbon solvent at a 
temperature of 30.degree. to 100.degree. C., and thereby, there is 
produced a solid catalyst component containing a hydrocarbyloxy group. 
In the above method, the preferred titanium compound is a compound of the 
formula: Ti(OR.sup.1).sub.n Cl.sub.4-n wherein R.sup.1 is as defined above 
and n is a number in the formula 2.ltoreq.n.ltoreq.4. 
(2) In Japanese Patent First Publication No. 30407/1981, there is disclosed 
the following method for preparing a solid catalyst component. 
An organic magnesium compound is reacted with at least one of the following 
halogen-containing compounds (I) and (II): 
(I) a halogenated silicon compound of the formula: R.sub.n SiCl.sub.4-n 
wherein R is a hydrocarbon group having 1 to 8 carbon atoms, and n is a 
number in the formula 0.ltoreq.n.ltoreq.4, 
(II) a halogenated aluminum compound of the formula: R.sub.l AlCl.sub.3-l 
wherein R is a hydrocarbon group having 1 to 8 carbon atoms, and l is a 
number in the formula 0.ltoreq.l&lt;3, a group of compounds (III) which 
comprises at least two compounds selected from compounds containing at 
least one of an N atom, O atom, P atom and S atom (wherein the at least 
two compounds are compounds having different bonding, and a titanium 
compound having at least one titanium-chlorine bond. 
In the above method, it is preferable to use a chlorinated silicon compound 
as the chlorine-containing compound and to use a phenol and an ester 
compound as the group of compounds (III). 
(3) In Japanese Patent Application No. 138471/1983 (Japanese Patent First 
Publication No. 28405/1985), there is disclosed the following method for 
preparing a solid catalyst component. 
Titanium tetrachloride is reduced by an organic aluminum compound of the 
formula: R.sup.1.sub.n AlY.sub.3 -n wherein R.sup.1 is a hydrocarbon group 
having 1 to 18 carbon atoms, Y is a halogen atom, and n is a number in the 
formula 1&lt;n&lt;3, and then subjected to a heat treatment at a temperature of 
150.degree. C. or lower to give a solid product containing .gamma.-type 
titanium trichloride. The solid product thus prepared is subjected to 
pre-polymerization with an .alpha.-olefin and then reacted with a halogen 
of the formula: X.sub.2 wherein X is Cl, Br or I, and/or a halogen-halogen 
compound of the formula: X'--X".sub.a wherein X' and X" are each Cl, Br or 
I and a is 1 or 3, and also with an ether compound of the formula: R.sup.2 
--O--R.sup.3 wherein R.sup.2 and R.sup.3 are the same or different and are 
each an alkyl group having 1 to 10 carbon atoms at a temperature of 
50.degree. to 100.degree. C. 
In the above method, the reduction of titanium tetrachloride with the 
organic aluminum compound is preferably carried out within a short period 
of time. 
(B) Organic aluminum compound 
The organic aluminum compound of the formula R.sub.e AlX.sub.3-e wherein R 
is a hydrocarbon group having 1 to 18 carbon atoms, X is a halogen atom, 
and e is a number in the formula 1.ltoreq.e.ltoreq.3, includes, for 
example, triethylaluminum, triisobutylaluminum, diethylaluminum hydride, 
diethylaluminum chloride, diethylaluminum bromide, ethylaluminum 
sesquichloride, ethylaluminum dichloride, and the like. Among these 
compounds, triethylaluminum, diethylaluminum chloride and a mixture 
thereof are particularly preferable in view of the well balanced 
polymerization activity and stereoregularity. 
(C) Electron donor 
The catalyst system used in the present invention comprises the solid 
catalyst component comprising a titanium compound and the organic aluminum 
compound. To further improve the polymerization activity and/or 
stereoregularity, it is advisable to use an electron donor (C). 
The electron donor includes, for example, esters, such as ethyl acetate, 
.epsilon.-caprolactone, methyl methacrylate, ethyl benzoate, ethyl 
p-anisilate, and methyl-p-toluylate; acid anhydrides, such as anhydrous 
phthalic acid; ether compounds, such as di-n-butyl ether, diphenyl ether, 
diglyme; organic phosphorus compounds, such as tri-n-butyl phosphite, 
triphenyl phosphite, hexamethylene phosphoric triamide; organic silicon 
compounds having an Si--O--C bond, such as alkoxysilanes, aryloxysilanes; 
and the like. Other compounds such as ketones, amines, amides and 
thioethers may also be used. Preferred electron donors are esters, 
phosphites and organic silicon compounds. In the case of a solid catalyst 
component comprising titanium, magnesium and halogen which are carried on 
a carrier, aromatic monocarboxylic acid esters and organic silicon 
compounds are particularly preferable electron donor. 
In the catalyst system, the ratio of each of the components are as follows. 
The organic aluminum compound (B) is preferably contained in an amount of 
0.1 to 1,500 mole per 1 mole of titanium in the solid catalyst component 
(A). When the solid catalyst component is mainly composed of trivalent 
titanium compound, the organic aluminum compound is preferably contained 
in an amount of 1 to 30 mole per 1 mole of titanium in the solid catalyst 
component. In the case of a solid catalyst component which is carried on a 
carrier such as a magnesium compound and silica gel, the organic aluminum 
compound is preferably contained in an amount of 40 to 1,500 mole per 1 
mole of titanium in the solid catalyst component. 
The electron donor is preferably contained in an amount of not more than 1 
mole per 1 mole of the organic aluminum compound. 
The organic aluminum compound and/or electron donor may also be added in 
the second step of the polymerization reaction. 
The polymerization reaction is described in more detail below. 
Production of propylene-ethylene block copolymer; 
According to this invention, the propyleneethylene block copolymer is 
produced by a two step polymerization reaction using the above-mentioned 
catalyst system. In this case, to produce the desired polymer particles 
having a smaller adhesion force and excellent physical properties, it is 
necessary to use a catalyst system having high stereoregularity. When the 
polymerization reaction is carried out by using a catalyst system having 
low stereoregularity, the produced polymer particles have a significantly 
increased adhesion force and also show less toughness and less heat 
resistance. It has been found that it is preferable to polymerize so that 
when the monomers are reacted in liquefied propylene at 65.degree. C. for 
4 hours, the polymer contains a component soluble in xylene at 20.degree. 
C. in an amount of not more than 5% by weight, more preferably not more 
than 4% by weight, to obtain the desired polymer having excellent physical 
properties and the preferred state of the polymer particles. 
When the monomers are polymerized in the first step by using a high 
capacity catalyst system, the amount of non-crystalline polymer varies 
depending on the amount of comonomer. It is preferable to control the 
production of a component soluble in xylene at 20.degree. C. to the range 
of not more than 15% by weight, more preferably not more than 5% by 
weight. 
The solid catalyst component may previously be subjected to polymerization 
of at least one .alpha.-olefin having 2 to 6 carbon atoms, preferably 
either ethylene or propylene, in an amount of not more than 1,000 g, 
preferably not more than 100 g, per 1 g of the solid catalyst component in 
the presence of an organic aluminum compound and/or an electron donor. The 
resulting composition is used as a solid catalyst component. 
The first step of the polymerization reaction of this invention can be 
carried out in liquefied propylene and/or in a gaseous phase in the 
presence of a catalyst system. That is, the polymerization can be carried 
out by reacting the monomers in liquefied propylene, or by reacting 
monomers first in liquefied propylene and then in a gaseous phase, or by 
reacting the monomers in a gaseous phase, but the polymerization in a 
gaseous phase is preferable because the flash distillation of liquefied 
propylene can be omitted. Hence, undesirable adhesion of soluble polymer 
onto the wall of the reaction vessel during the flashing of liquefied 
propylene can be avoided. 
The feature of the first step of polymerization is specifically mentioned 
below. 
The polymerization may occur by homopolymerization of propylene, or by 
copolymerization of propylene and a comonomer such as ethylene or an 
.alpha.-olefin having 4 to 6 carbon atoms. It is preferable to regulate 
the amount of the comonomer so that the polymer produced in this first 
step has a comonomer content of not more than 6% by mole, more preferably 
not more than 4% by mole. When the comonomer content is over 6% by mole 
(or in a more preferable feature, over 4% by mole), the block copolymer 
shows an inferior flexural modulus and inferior heat resistance. The 
polymerization in liquefied propylene is preferably carried out at a 
temperature of 40.degree. to 90.degree. C. under a pressure of 17 to 50 
kg/cm.sup.2. The polymerization in a gaseous phase is preferably carried 
out at a temperature lower than the melting point of the polymer, more 
preferably at 40.degree. to 100.degree. C., under a pressure of from 
atmospheric pressure to 40 kg/cm.sup.2 under the conditions that the 
monomers are not liquified within the reaction vessel. In this first step, 
it is further preferable to add a molecular weight regulating agent (e.g. 
hydrogen, etc.) to the reaction system in order to improve the melt flow 
properties of the final product. 
The polymerization in the second step is carried out consequently after the 
polymerization in the first step. The polymerization is carried out by 
homopolymerizing ethylene in a gaseous phase, or by copolymerizing 
ethylene with propylene and/or an .alpha.-olefin having 4 to 6 carbon 
atoms so that the produced polymer has an ethylene content of not less 
than 10% by mole. This second step may also be carried out in a liquefied 
monomer comprising mainly propylene or in an inert hydrocarbon (e.g. 
hexane, heptane, etc.). However, when it is done in a liquefied monomer, 
too high of a polymerization pressure is required for increasing the 
ethylene content in the polymer produced in the step because the propylene 
partial pressure is high in the system, which is disadvantageous in that a 
high capacity apparatus is needed and further that low-crystalline polymer 
soluble in the liquefied monomers is increased in the range of ethylene 
content of 20 to 80% by mole. Therefore, the polymer is precipitated in 
the step of flashing of the liquefied monomers to induce fouling within 
the flashing vessel. It is also undesirable to conduct the polymerization 
in an inert hydrocarbon, because the soluble low-crystalline polymer is 
also increased. 
The polymer produced in this second step has preferably an ethylene content 
of 20 to 80% by mole in view of the well balanced toughness and impact 
resistance of the block copolymer. The second step may be carried out in 
two or more stages by varying the concentration of ethylene. 
The polymerization in the second step is preferably carried out at a 
temperature of not higher than the melting point of the polymer, 
preferably 40.degree. to 100.degree. C., under a pressure of from 
atmospheric pressure to 40 kg/cm.sup.2 so that the monomers are not 
liquefied within the polymerization vessel. In order to regulate the melt 
flow properties of the final product, it is preferable to add a molecular 
weight regulating agent (e.g. hydrogen, etc.) to the reaction system in 
this second step. 
In this second step, the polymerization is carried out in the degree of 10 
to 70% by weight based on the whole polymerization amount, but it is 
preferable in the degree of 20 to 60% by weight, more preferably 25 to 50% 
by weight, because the resulting polymer has a well balanced adhesion 
force of polymer particles and impact resistance. When the polymerization 
amount in the second step is less than 10% by weight (in a preferred 
feature less than 20% by weight, in a more preferred feature less than 25 
% by weight), the resulting polymer exhibits inferior impact resistance. 
On the other hand, when the polymerization amount in the second step is 
more than 70% by weight (in a preferred feature more than 60% by weight, 
and in a more preferred feature more than 50% by weight), the resulting 
polymer particles have a disadvantageously increased adhesion force. 
The .alpha.-olefins having 4 to 6 carbon atoms used in this invention 
include, for instance, butene-1, pentene-1, hexene-1, 4-methylpentene-1, 
3-methylbutene-1, and the like. 
The present invention can provide propylene-ethylene block copolymer 
particles comprising substantially two segments and having a smaller 
adhesion force and a narrower particle distribution, wherein the first 
segment is formed in the first polymerization step and the second segment 
is formed in the second polymerization step. 
The adhesion force of the polymer particles is also effected by the 
molecular weight of the polymer produced in the second step, and when the 
molecular weight of the polymer produced in the second step is larger, the 
adhesion force of the resulting polymer particles is lowered and improved. 
However, when the molecular weight of the polymer produced in the second 
step is made larger, the block copolymer shows, to the contrary, inferior 
melt flow properties and also significantly inferior molding and 
processing characteristics. To achieve the desired stable molding and 
procesing of the polymer, the melt index should be in the range of not 
less than 0.3 g/10 minutes, preferably not less than 0.5 g/10 minutes, and 
more preferably not less than 1.0 g/10 minutes. Such a melt index is 
obtained by regulating the intrinsic viscosity of the polymer produced in 
the second step to the range of not more than 7 g/dl, preferably not more 
than 6 g/dl, and more preferably not more than 5 g/dl. 
According to this invention, even though a molecular regulating agent (e.g. 
hydrogen, etc.) is added in the second step to regulate the molecular 
weight of the produced polymer and thereby to improve the molding and 
processing characteristics of the product, the polymer particles 
demonstrate an extremely improved adhesion force. That is, there are 
obtained polymer particles having an adhesion force of not more than 6.0 
g/cm.sup.2, preferably not more than 5.0 g/cm.sup.2, and more preferably 
not more than 4.0 g/cm.sup.2. 
The reaction vessel for the gas phase polymerization in this invention is 
not critical, but includes any known vessel, such as an agitating type 
reaction vessel, a fluidized bed type reaction vessel, an agitating 
fluidized bed type reaction vessel, and the like. However, for 
homogeneously mixing the reaction mixture in the whole polymerization 
region and easily removing the heat of polymerization, it is preferable to 
employ a system wherein a part or whole of the gases to be polymerized in 
the system is removed from the reaction vessel, cooled and recycled to the 
reaction vessel. Particularly, a system of polymerizing in a fluidized 
bed, that is, a fluidized bed type reaction vessel and an agitating 
fluidized bed type reaction vessel are preferable. 
The polymerization reaction of the present invention may be continuously 
carried out by using two or more reaction vessels which are combined in 
series, or may be carried out in batch system by using one or more 
reaction vessels, or may be carried out in a combination of these systems. 
This invention is illustrated by the following examples but should not be 
construed to be limited thereto. 
The results in the Examples and the Reference Examples are shown in Tables 
1 to 4 and FIG. 1 to 5. In the tables, the properties are measured by the 
following methods. 
Melt index: by a method as set forth in ASTM D1238 
Flexural rigidity: by a method as set forth in ASTM D747 
Vicat softening point: by a method as set forth in ASTM D1525 
Izod impact strength: by a similar method as set forth in ASTM D256, 
measured at 23.degree. C., 0.degree. C., -20.degree. C. and -30.degree. C. 
Tensile test: by a similar method as set forn in ASTM D638, measured as to 
yield stress (YS), ultimate strength (US) and ultimate elongation (UE) 
Intrinsic viscosity [.eta.]: measured in Tetralin at 135.degree. C. 
[.eta.].sub.P : it shows the intrinsic viscosity of the polymer produced in 
the first step. 
[.eta.].sub.T : it shows the intrinsic viscosity of whole polymer. 
[.eta.].sub.EP : it shows the intrinsic viscosity of the polymer produced 
in the second step. 
The [.eta.].sub.EP is calculated by the following equation: 
##EQU2## 
wherein (P): the ratio of the polymerization amount in the first step 
(ratio by weight) 
(EP): the ratio of the polymerization amount in the second step (ratio by 
weight) 
Adhesion force of the polymer particles: Two shear testing cells made from 
an aluminum plate (width 30 mm, length 53 mm, height 12 mm) were piled on 
each other in contact, and between them polymer particles to be measured 
were entered and subjected to pilot pressure under a load of 1,000 g for 
30 seconds and then subjected to the shear test under a normal load of 50 
g, 100 g, 200 g, 300 g, and 400 g, at a room temperature and at a take-off 
speed of 100 mm/minute, whereby the shear stress under each normal load 
was measured. The correlation between the values of the normal load and 
the values of the measured shear stress were drawn in an approximate 
straight line by using a minimum square method, and the shear stress at a 
point on the line which was extrapolated to the normal load 0 (zero) g was 
counted as the adhesion force. 
Component soluble in xylene at 20.degree. C. (hereinafter referred to as 
"CXS"): The polymer (1 g) was dissolved in boiling xylene (200 ml) and the 
mixture was gradually cooled to 50.degree. C. and further cooled to 
20.degree. C. by dipping in ice water with stirring, and the mixture was 
allowed to stand at 20.degree. C. for 3 hours, and then the precipitated 
polymer was separated by filtration. The filtrate was distilled to remove 
xylene, and the residue was dried in vaccuo, and the polymer was 
recovered. This polymer was the component soluble in xylene at 20.degree. 
C. 
Ethylene content: measured by utilizing the known absorption band in an 
infrared absorption spectrum. The ethylene content thus measured was 
corresponded well to the value calculated from the balance between the 
amount of the starting materials and the yield. 
Particle distribution: measured by using an optical transmission type 
device for measuring particle distribution (manufactured by Seishin Kigyo 
K.K., Japan) employing as a solvent decalin. 
Pore volume: measured by using Porosimeter Series 800 (manufactured by 
Carlo Erba Co.) in the range of pore radius of 75 .ANG. to 75,000 .ANG.. 
EXAMPLE 1 
(1) Preparation of a solid catalyst component: 
A 200 liter reactor was purged with nitrogen and thereto were added hexane 
(26 liter) and tetrabutoxytitanium (28.6 kg). The mixture was agitated at 
an agitation speed of 120 r.p.m. at an inner temperature of 35.degree. C. 
A 40% by weight solution of ethylaluminum sesquichloride in hexane (53 kg) 
was added dropwise to the mixture over a period of 3 hours while keeping 
the temperature of the system at 35.degree. C. After the addition, the 
mixture was agitated at 35.degree. C. for 30 minutes and then heated at 
60.degree. C. for one hour. The reaction mixture was filtered and washed 
with hexane (100 liters) three times to obtain a solid product. 
To the above reaction product was added hexane (120 liter) so as to make 
the solid product slurry and thereto was added triethylaluminum (1.5 kg). 
The mixture was heated to 50.degree. C. while agitating at an agitation 
speed of 100 r.p.m. Ethylene monomer (3.5 kg) was added gradually over a 
period of one hour at 50.degree. C., and subjected to a 
pre-polymerization. After the pre-polymerization, the reaction mixture was 
filtered to obtain an ethylene-pre-polymerized solid product. The 
ethylene-pre-polymerized solid product was made into a slurry with heptane 
(120 liter), and to the mixture was added diisoamyl ether (16 liter) while 
keeping the temperature of the system at 30.degree. C. After reacting at 
30.degree. C. for one hour, the mixture was heated to 75.degree. C. and 
thereto was added titanium tetrachloride (15 liter), and the mixture was 
further reacted at 75.degree. C. for one hour. After the reaction, the 
reaction mixture was filtered, and the residue was washed with heptane 
(100 liter) three times. After the washing, the product was again treated 
with isoamyl ether and titanium tetrachloride in the same manner as 
described above. 
After the reaction, the reaction product was washed with hexane (100 liter) 
six times and dried to give a solid catalyst component (1) (15.2 g), which 
contained trivalent titanium atom 22.1% by weight, isoamyl ether 6.9 % by 
weight, chlorine 47.7% by weight, and butoxy group 0.4 % by weight. 
The particle distribution of the product is shown in FIG. 3. The solid 
catalyst component had a mean particle size (Dg) of 30 .mu.m, a standard 
deviation (.sigma.g) of the particle distribution of 1.4., and a pore 
volume in the range of pore radius of 200 to 15,000 .ANG. of 0.19 cc/g. 
The solid catalyst component (1) was evaluated as to the stereoregularity 
and polymerization activity by subjecting it to a polymerization of 
propylene in a one liter reaction vessel as follows. 
Th reactor was purged with argon and thereto were added the solid catalyst 
component (1) (17.0 mg) and diethylaluminum chloride (1.5 g), and to the 
mixture was added hydrogen until the hydrogen partial pressure became 0.6 
kg/cm.sup.2 and was further added propylene (280 g). The mixture was 
heated to 65.degree. C. to initiate the polymerization reaction. After 
polymerization for 4 hours, the unreacted monomer was purged off to give 
white powdery polypropylene (120 g). The polypropylene was obtained in an 
amount of 7,060 g per 1 g of the solid catalyst component (1). 
The component soluble in xylene at 20.degree. C. was measured. As a result, 
it was 2.2% by weight, which means that it is excellent in 
stereoregularity and in polymerization activity. 
(2) Preparation of a pre-polymerization catalyst: 
A reactor having an inner value of 300 liters and an agitator was purged 
with nitrogen and thereto were added the solid catalyst component (1) 
(2.15 kg) as prepared above (1), butane (100 liter) and diethylaluminum 
chloride (938 g), and agitation of the mixture was started. Thereto was 
added propylene under a pressure of 5 kg/cm.sup.2 at 40.degree. C. After 
polymerization for 2.45 hours, the supplement of propylene was stopped. 
The reaction mixture was filtered with a filter provided at the bottom of 
the reactor. To the reaction mixture was added butane (100 liter), and the 
mixture was agitated. The reaction mixture was filtered to give a 
pre-polymerization catalyst. The pre-polymerization catalyst was 
transferred to a jacketed drum provided with a nozzle for supplying 
nitrogen at the bottom, and then dried by supplying a small amount of 
nitrogen by a flowing a hot water of 50.degree. C. into the jacket to 
obtain a pre-polymerization catalyst (26.9 kg). 
(3) Block copolymerization of propylene-ethylene: 
Block copolymerization of propylene-ethylene was carried out by a two step 
reaction using an agitating fluidized bed type reaction vessel (inner 
volume 1 m.sup.3) as shown in FIG. 1, and the polymerization was repeated 
five times. 
The reactor was first purged with dewetted nitrogen and thereto were 
circulated gases at a rate of 100 m.sup.3 /hour with a gas-circulator (10) 
provided on the circulation line. The gases were circulated in such an 
amount that the polymer particles were kept in a flowing state through 
whole step of the polymerization, and the circulation amount of the gases 
was kept at constant until the polymer particles were removed from the 
reactor after completion of the polymerization. To the reactor were added 
polypropylene particles (propylene homopolymer of [.eta.]: 1.7 dl/g, mean 
particle size: 600 .mu.m) (60 kg) to disperse the catalyst, and the 
content within the reactor was replaced by propylene. Thereafter, 
propylene and hydrogen were added to raise the inner pressure till 5 
kg/cm.sup.2 (gauge pressure "G") and to reach a hydrogen concentration of 
6.3% by mole. A promotor component mentioned below was supplied from a 
nozzle (6) under pressure with hydrogen. Diethylaluminum chloride (160 g) 
and then the pre-polymerization catalyst obtained in (2) (66.3 g) were 
supplied from a nozzle (5). 
In the first step of the polymerization, the temperature within the reactor 
was raised to 65.degree. C. and the reactor was kept under a pressure of 5 
kg/cm.sup.2 G for one hour, and the pressure was raised to 19.7 
kg/cm.sup.2 G and the polymerization was continued. During the first step, 
hydrogen was continuously supplied to keep the hydrogen concentration of 
6.3% by mole. When the amount of polymerization became 32 kg, the 
unreacted monomer was purged until the inner pressure lowered to 11 
kg/cm.sup.2 G. 
In the second step of the polymerization, while keeping the inner 
temperature at 65.degree. C., ethylene and propylene were supplied so that 
the ethylene concentration became 16% by mole and the pressure became 15 
kg/cm.sup.2 G. After the pressurization, ethylene, proplene and hydrogen 
were supplied so that the concentrations of ethylene and hydrogen were 
kept at 16% by mole and 6% by mole, respectively and also the pressure was 
kept at 15 kg/cm.sup.2 G. When the amount of polymerization became 18 kg, 
the content was purged until the inner pressure lowered to 5 kg/cm.sup.2 
G. The polymer particles thus produced were removed from the reactor so 
that the polymer particles were retained in an amount of 60 kg. Then, the 
first series of polymerization was completed. 
The second series of polymerization was conducted by replacing ethylene by 
propylene until the ethylene concentration became not more than 0.1% by 
mole, supplying propylene and hydrogen so that the pressure became 5 
kg/cm.sup.2 G and the hydrogen concentrtion became 6.3% by mole, and then 
supplying the same catalyst component as used in the first polymeriation 
except that diethylaluminum chloride was used in an amount of 73 g. The 
second series of polymerization was carried out under the same conditions 
as in the first series of polymerization except that the retained polymer 
particles obtained in the first polymerization were used for the 
dispersion of catalyst. 
The polymerization as above was repeated five times, and the whole of the 
resulting polymer particles were removed from the reactor. The polymer 
particles thus removed were transferred to a 200 liter agitating vessel, 
and thereto were added propylene oxide (100 g) and methyl alcohol (60 g), 
and the mixture was heated at 80.degree. C. for 2 hours. The reaction 
mixture was dried at 80.degree. C. while ventilating nitrogen to give 
white powdery polymer. 
By the above polymerization, there was obtained the polymer in an amount 
9,400 g per 1 g of the solid catalyst component (1). The results of the 
polymerization are shown in Table 1 and FIG. 5. Even though the 
polymerization in the second step was carried out in a polymerization 
amount of 36% by weight based on the whole polymerization amount, the 
polymer particles showed an adhesion force of 2.5 g/cm.sup.2, which is 
excellent. 
The removal of the polymer particles from a nozzle (13) provided in the 
reactor could be carried out without any problem. When the amount of the 
polymer particles collected at a cyclone (7) was measured to evaluate the 
fly of polymer particles from the reactor, it was 450 g, which did not 
present any problems for operation. 
After the polymerization procedure, the reactor was checked. As a result, 
the adhesion of the polymer onto the inner wall and agitator was so small 
that the metallic surface was highly visible, which did not cause any 
problems. 
The polymer particles obtained above were mixed with calcium stearate (0.1% 
by weight), 2,6-di-tert.-butyl-p-cresol (0.2% by weight), and 
tetrakis[methylene-3-(3,5-di-tert.-butyl-4-hydroxyphenol)propionate]methan 
e (0.1% by weight), and the mixture was extruded in the form of strands by 
an extruder provided with a screw (diameter 40 mm .phi.) and then 
pelletized. In this case, the polymer particles could be extruded from the 
hopper of the extruder without any problem of bridging and surging, etc. 
The properties of the pellets thus prepared were measured. The results are 
shown in Table 2. As is clear from Table 2, the product had very excellent 
impact strength even at a low temperature. The formed product did not show 
any problem such as coloring. 
The component soluble in xylene at 20.degree. C. of the polymer obtained in 
the first step of this example was measured by the same polymerization in 
the first step using the same catalyst component as used in the example. 
As a result, it was 2.9% by weight. 
EXAMPLES 2 TO 4 AND REFERENCE EXAMPLES 1 TO 5 
The block copolymerization of propylene-ethylene was carried out by a two 
step reaction using a 5 liter autoclave provided with an agitator. The 
autoclave was dried for one hour under a reduced pressure with a vacuum 
pump and thereto were added diethylaluminum chloride diluted with a small 
amount of heptane (hereinafter, referred to as "DEAC") and a solid 
catalyst containing titanium trichloride. The pressure of this vessel was 
raised with hydrogen (H.sub.2) and thereto was supplied liquefied 
propylene, and the first step polymerization was initiated after 
regulating the temperature at 60.degree. C. After polymerization for one 
hour, unreacted monomer was purged off, and then a small amount of polymer 
was removed as a sample for measuring [.eta.].sub.p and CXS. Thereto was 
supplied H.sub.2, and the pressure was raised to 6.9 kg/cm.sup.2 G by 
adding propylene and further to 10 kg/cm.sup.2 G by adding ethylene. After 
regulating the temperature to 60.degree. C., the second step of 
polymerization was initiated. During the second step, the pressure was 
maintained at 10 kg/cm.sup.2 G by supplying a mixture of ethylene and 
propylene (molar ratio: 50/50). When the polymerization amount of in the 
second step reached the desired degree, unreacted monomer was purged off. 
The amounts of polymerization in the first step and the second step and 
the ratio thereof were calculated based on the amounts of the starting 
materials and the products. 
The polymerization conditions and results are shown in Table 3 and Table 4 
and FIG. 3, 4 and 5, respectively. 
In Examples 2 to 4, the block copolymerization of propylene and ethylene 
was conducted by varying the amount of polymerization in the second step 
using the solid catalyst component (1). With an increase of in the amount 
of polymerization in the second step, the polymer particles showed a 
somewhat increased adhesion force, but the adhesion force was still at a 
good level. As shown in Example 4, even when the ratio of the amount of 
polymerization in the second step was 41% by weight, the adhesion force of 
the polymer particles presented still in 3.1, which was no problems. 
In Reference Examples 1 to 3, the block copolymerization of propylene and 
ethylene was carried out by using a solid catalyst component which had a 
narrower .DELTA.V.sub.P than that used in the present Examples. In the 
Reference Examples, the adhesion force of the polymer particles relative 
to the amount of polymerization in a second step was significantly higher 
than that in the present Examples. In Reference Example 2, the polymer 
particles showed an adhesion force as high as 7.9 g/cm.sup.2, and when 
checked after the polymerization, the reactor was lamellarly adhered with 
a significantly large amount of polymer particles on the inner wall and 
the adhered polymer particles were almost solidified. 
In Reference Example 4, the block copolymerization of propylene and 
ethylene was carried out by using a solid catalyst which had the same 
range of .DELTA.V.sub.P as in the present Examples but had a wider range 
of particle distribution and contained a large amount of fine particles. 
The adhesion force of the polymer particles relative to the polymerization 
amount in the second step was higher than that in the present Examples. 
After the polymerization, the reactor was checked, and as a result, fine 
particles were adhered onto the inner wall and the agitator in a thin 
layer. There were observed many chunks having a diameter of 5 to 10 mm. To 
measure the relationship of the particle size of the polymer particles and 
the adhesion force of the particles, the adhesion force of the particles 
was measured in the following screened classes in particle size. The 
results are shown in the following table. 
______________________________________ 
Particle size (.mu.m) 
Adhesion force (g/cm.sup.2) 
______________________________________ 
Non-screened 4.5 
Less than 500 5.6 
500-1,000 2.2 
More than 1,000 
1.7 
______________________________________ 
As is clear from the above result, the particle size has a close 
relationship with the adhesion force of the polymer particles, and with a 
decrease in the particle size, the adhesion force increases significantly. 
Thus, to improve the adhesion force of the polymer particles, it is 
necessary to decrease the amount of fine particles. 
In Reference Example 5, the polymerization was carried out by modifying the 
conditions so that the amount of hydrogen supplied in the second step was 
lowered to increase the molecular weight of the produced polymer. The 
polymer produced in the second step showed [.eta.] of 8.2 dl/g. When 
compared with Reference Example 4 wherein the molecular weight of the 
polymer was decreased while using the same catalyst system, the polymer 
particles showed an improved adhesion force. On the contrary, the product 
showed a lower melt index which is an index factor for showing the molding 
and processing characteristics. Thus, the product in this Reference 
Example 5 had significantly inferior molding and processing 
characteristics. 
The solid catalyst components as used in the Examples and Reference 
Examples were prepared as follows. 
(i) There was used SOLVAY CATALYST.RTM. (manufactured by Marubeni-Solvay 
Co.) as the solid catalyst component (2). This solid catalyst component 
had a Dg of 19 .mu.m, .sigma.g of 1.3 and further a pore volume in a range 
of a pore radius of 200 to 15,000 .ANG. of 0.02 cc/g. When the 
polymerization capacity thereof was measured in the same manner as 
described in Example 1-(1), it produced polypropylene in an amount of 
7,400 g per 1 g of the solid catalyst component. Besides, the polymer 
contained CXS of 3.5% by weight. 
(ii) Preparation of the solid catalyst component (3): 
The solid catalyst component was prepared in the same manner as described 
in Example 1 except that no pre-polymerization with ethylene occurred. The 
solid catalyst component contained trivalent titanium component 28.7% by 
weight, isoamyl ether 7.2% by weight, chlorine 61.6% by weight, and butoxy 
group 0.5% by weight. 
When the the distribution of particles was measured, the solid catalyst 
component showed a Dg of 22 .mu.m, .sigma.g of 2.5, and a pore volume in 
the range of a pore radius of 200 to 15,000 .ANG. of 0.50 cc/g. 
When the polymerization capacity thereof was measured under the same 
conditions as in Example 1, polypropylene was produced in an amount of 
8,910 g per 1 g of the solid catalyst component and the polymer contained 
CXS of 2.4% by weight. 
EXAMPLE 5 
This example was carried out by using a solid catalyst on a carrier. 
(1) Preparation of solid catalyst component (4): 
(A) Preparation of an organic magnesium compound: 
A 200 liter reactor was purged with nitrogen and thereto were added metal 
magnesium (3.5 g), di-n-butyl ether (44 liter) and a small amount of 
Grignard reagent. While the mixture was agitating at an agitation speed of 
75 r.p.m. and keeping the inner temperature at 50.degree. C., n-butyl 
chloride (15 liter) was added dropwise over a period of 5 hours. After the 
addition, the mixture was further reacted at 50.degree. C. for 2 hours, 
and thereafter, the reaction mixture was cooled to room temperature, and 
the solid product was obtained by filtration. 
The n-butylmagnesium chloride in di-n-butyl ether was hydrolyzed with 1N 
sulfuric acid and back-titrated with 1N NaOH to determine the 
concentration thereof (indicator: phenolphthalein). As a result, the 
concentration thereof was 2.26 mole/liter. 
(B) Preparation of a carrier: 
Subsequently, silicon tetrachloride (12.8 liter) was added dropwise to a 
solution of n-butylmagnesium chloride in di-n-butyl ether over a period of 
6 hours, while agitating at an agitation speed of 75 r.p.m. and keeping 
the inner temperature at 20.degree. C. After the addition, the mixture was 
further agitated at 20.degree. C. for one hour, and the reaction mixture 
was filtered and washed with hexane (100 liter) four times to obtain a 
carrier. 
(C) Treatment with phenol/ethyl benzoate: 
The carrier prepared in the above (B) was made into a slurry with hexane 
(70 liter), and then the inner temperature was kept at 60.degree. C. 
To the mixture were added a solution of phenol (4.2 kg) in hexane (100 
liter) and ethyl benzoate (6.4 liter), and the mixture was reacted at 
60.degree. C. for 30 minutes. The reaction mixture was filtered and washed 
with hexane (150 liter) three times at 60.degree. C. 
(D) Preparation of solid catalyst component: 
To the above product was added monochlorobenzene (80 liter) to make it into 
a slurry, and thereto was added a solution of a compound of the formula: 
##STR1## 
(122.4 g) in monochlorobenzene (48 liter), and the mixture was reacted at 
100.degree. C. for 30 minutes. After the reaction, the reaction mixture 
was filtered at 100.degree. C. and washed at 100.degree. C. with toluene 
(150 liter) one time and with hexane (100 liter) three times, and dried to 
give the solid catalyst component (4) (15.1 kg). 
The solid catalyst component (4) contained titanium (2.5% by weight), 
magnesium (20.9% by weight), chlorine (65.6% by weight), phenol (1.7% by 
weight), and ethyl benzoate (9.1% by weight). When the distribution of the 
particles was measured, it showed a Dg of 27 .mu.m, .sigma.g of 1.6, and a 
pore volume in the range of a pore radius of 200 to 15,000 .ANG. of 0.17 
cc/g. 
In order to evaluate the stereoregularity and polymerization activity of 
the solid catalyst component (4), it was subjected to a polymerization of 
propylene in a 5 liter reactor. That is, the reactor was purged with argon 
and thereto were added the solid catalyst component (4) (19 mg), 
triethylaluminum (0.65 g) and methyl p-toluylate (0.26 g), and thereto 
were supplied hydrogen in a partial pressure thereof of 3 kg/cm.sup.2 and 
further propylene (1,000 g), and the temperature was raised to 65.degree. 
C. to initiate the polymerization. After reacting for 1.5 hour, the 
unreacted monomer was purged off to obtain white powdery polypropylene 
(165 g). In this polymerization, polypropylene was produced in an amount 
of 8,680g per 1 g of the solid catalyst component (4). Besides, the 
polymer contained a component soluble in xylene at 20.degree. C. of 3.6% 
by weight, which presented no problems in the stereoregularity and the 
polymerization activity. 
(2) Block copolymerization of propylene-ethylene: 
Block copolymerization of propylene-ethylene was conducted by two step 
reaction using a 5 liter autoclave provided with an agitator. The 
autoclave was dried for one hour under a reduced pressure with a vacuum 
pump, and thereto were supplied triethylaluminum (0.65 g) diluted with a 
small amount of heptane, methyl p-toluylate (0.26 g) and the solid 
catalyst component (4) (0.0237 g). The pressure of this vessel was raised 
with H.sub.2 to a partial pressure of 0.79 kg/cm.sup.2 and further with 
propylene to 4 kg/cm.sup.2 G, and then thereto was supplied a mixture of 
ethylene and propylene (ethylene/propylene=70/30 by mole) and the 
temperature was kept at 60.degree. C. During the second step 
polymerization, the pressure was kept at 7 kg/cm.sup.2 G by supplying the 
gas mixture. When the polymerization occurred for 3 hours, the unreacted 
monomer was purged off. The polymer particles thus obtained were treated 
and dried in the same manner as described in Example 1 to give white 
powdery polymer particles. The results of the polymerization are shown in 
Table 2. 
The relationship of the adhesion force of the polymer particles to the 
amount of polymerization in the second step were good and there was no 
problems. 
EXAMPLE 6 
By using a fluidized bed type reaction vessel (inner volume: 1 m.sup.3) 
which was arranged in series as shown in the accompanying FIG. 2, the two 
step block copolymerization of propylene ethylene was continuously carried 
out. The two reactors were arranged in the same manner as in Example 1. 
The reactor A and reactor B were kept under the reaction conditions as 
shown in the following table. 
______________________________________ 
Reaction conditions 
Reactor A 
Reactor B 
______________________________________ 
Pressure (kg/cm.sup.2 G) 
20 16 
H.sub.2 concentration (molar %) 
14.8 6.5 
Ethylene concentration (molar %) 
0 17 
Held up amount of polymer (kg) 
65 85 
Circulation amount of gas (m.sup.3 /hr.) 
120 100 
Mean temperature in polymer phase 
65 65 
(.degree.C.) 
______________________________________ 
A catalyst component having the following composition was continuously 
supplied to the polymer phase within the reactor A. 
______________________________________ 
Catalyst component 
______________________________________ 
The pre-polymerization catalyst as used 
1.2 g/hr. 
in Example 1 [calculated by converson to 
the solid catalyst component (1)] 
Diethylaluminum chloride 
7.6 g/hr. 
Triethylaluminum 0.72 g/hr. 
Methyl methacrylate 1.1 g/hr. 
______________________________________ 
The polymerization reaction was continued for 170 hours after the 
initiation of the supplement of the catalyst. The mean polymerization 
amount in each reactor was calculated from the differences between the 
amounts of the starting materials and that of the product. As a result, 
the polymerization amount was 6.1 kg/hr. in the reactor A and 4.2 kg/hr. 
in the reactor B, respectively. 
The polymerization results are shown in Table 1 and FIG. 5. 
During the polymerization reaction, there was no problem in the operation 
of the reactor A and the reactor B, and the removal of the polymer from 
each reactor was carried out without any problem. Besides, after the 
polymerization, each reactor was checked. As a result, while there was 
observed some adhesion of the polymer on the wall at the position 
corresponding to the diluted phase of the polymer, at the position 
corresponding to the concentrated phase of the polymer, the metallic 
surface was observed. Thus, there was no problem in terms of the adhesion 
of the polymer. 
The polymer particles thus obtained were mixed with additives as in Example 
1 and pelletized with an extruder equipped with a screw (diameter 40 
mm.phi.). The polymer particles could be supplied from the hopper in the 
extruder without any problem of bridging. The properties of the polymer 
particles were measured by using the pellets thus obtained, and the 
results are shown in Table 2. As is clear from Table 2, the polymer 
particles showed an extremely excellent impact resistance even at a low 
temperature. 
REFERENCE EXAMPLE 6 
By using the same apparatus as used in Example 6, the two step block 
copolymerization of propylene-ethylene was continuously carried out in the 
same manner as described in Example 1 except that the catalyst components 
to be supplied and the polymerization conditions were changed as follows. 
______________________________________ 
Reaction conditions 
Reactor A 
Reactor B 
______________________________________ 
Pressure (kg/cm.sup.2 G) 
20 14 
H.sub.2 concentration (molar %) 
3.7 3.6 
Ethylene concentration (molar %) 
0 17 
Held up amount of polymer (kg) 
70 60 
Circulation amount of gas (m.sup.3 /hr.) 
120 100 
Mean temperature in polymer phase 
65 65 
(.degree.C.) 
______________________________________ 
The pre-polymerization catalyst was prepared in the same manner as 
described in Example 1 except that the solid catalyst component (2) was 
used. The value in the table was shown by converting to the solid catalyst 
component (2). 
______________________________________ 
Catalyst component 
______________________________________ 
The pre-polymerization catalyst 
1.4 g/hr. 
[calculated by conversion to 
the solid catalyst component (2)] 
Diethylaluminum chloride 
8.0 g/hr. 
Triethylaluminum 0.62 g/hr. 
Methyl methacrylate 1.3 g/hr. 
______________________________________ 
The polymerization results are shown in Table 1 and FIG. 5, and the 
properties of the polymer thus obtained are shown in Table 2. 
During the polymerization reaction, there was no specific problem as to the 
reactor A, but in the reactor B, closing of the exit of the reactor and 
the line of 1 inch occurred four times when the polymer particles were 
taken out with a nozzle of 1 inch. Besides, after treating in a 200 liter 
agitating vessel, the polymer particles were hardly removed, contrary to 
Example 6, and a large amount of polymer particles remained in the 
reactor. When the reactors were checked, there was no problem as to the 
reactor A like in Example 6, but in the reactor B, tacky polymer (about 5 
kg) was adhered at the position corresponding to the lower region of the 
concentrated phase of the polymer. Besides, at the position corresponding 
to the diluted phase of the polymer, tacky polymer was adhered in a 
lamellar state. The polymer had significantly inferior impact strength at 
a low temperature as compared to the product in Example 6. 
TABLE 1 
__________________________________________________________________________ 
Mean Ratio of poly- 
Adhesion force 
particle Ethylene 
merization amount 
of polymer 
size [.eta.]p 
[.eta.].sub.T 
content 
in second step 
particles 
Ex. No. 
(.mu.m) 
.sigma.g 
(dl/g) 
(dl/g) 
(wt. %) 
(wt. %) (g/cm.sup.2) 
__________________________________________________________________________ 
Ex. 1 
640 1.3 
1.71 
2.06 
14.8 36 2.5 
Ex. 6 
620 1.3 
1.53 
2.26 
13.9 41 2.8 
Ref. 630 1.2 
2.12 
2.42 
8.0 20 7.2 
Ex. 6 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Exam- Exam- Ref. 
Items Unit ple 1 ple 6 Ex. 6 
______________________________________ 
Melt index g/10 min. 4.0 3.4 2.3 
Flexural rigidity 
kg/cm.sup.2 
5,900 4,800 9,200 
Vicat softening point 
.degree.C. 51 45 77 
Izod impact 
23.degree. C. 
kg .multidot. cm/cm.sup.2 
70 73 51 
strength 
0.degree. C. 79 -- 9.5 
-20.degree. C. 19 37 4.5 
-30.degree. C. 12 13 3.5 
Tensile test 
YS kg/cm.sup.2 
160 150 250 
US kg/cm.sup.2 
160 170 340 
UE % 480 570 770 
______________________________________ 
TABLE 3 
__________________________________________________________________________ 
Catalyst components First step Second step 
DEAC Polymeri- Polymeri- 
Ex. 
Solid cat. compt. 
Amount 
H.sub.2 
Propylene 
zation 
H.sub.2 
zation 
No. 
Kind Amount (g) 
(g) (atm) 
(g) time (hr.) 
(atm) 
time (hr.) 
__________________________________________________________________________ 
Ex. 2 
Solid cat. 
0.0869 
3.0 2.8 1,200 1.0 0.79 
2.5 
compt. (1) 
Ex. 3 
Solid cat. 
0.0877 
3.0 2.8 1,200 1.0 0.79 
3.1 
compt. (1) 
Ex. 4 
Solid cat. 
0.0956 
3.0 2.8 1,200 1.0 0.79 
3.4 
compt. (1) 
Ref. 
Solid cat. 
0.0973 
3.0 2.8 1,200 1.0 0.79 
1.3 
Ex. 1 
compt. (2) 
Ref. 
Solid cat. 
0.1084 
3.0 2.8 1,200 1.0 0.79 
1.4 
Ex. 2 
compt. (2) 
Ref. 
Solid cat. 
0.0932 
3.0 2.8 1,200 1.0 0.79 
1.7 
Ex. 3 
compt. (2) 
Ref. 
Solid cat. 
0.1126 
3.0 2.8 1,200 1.0 0.79 
1.8 
Ex. 4 
compt. (3) 
Ref. 
Solid cat. 
0.1034 
3.0 2.8 1,200 1.0 0.06 
1.8 
Ex. 5 
compt. (3) 
__________________________________________________________________________ 
TABLE 4 
__________________________________________________________________________ 
Adhesion 
Polymeri- Ratio of 
force of 
zation 
Mean Ethylene 
polymerization 
polymer 
CXS in 
Ex. 
amount 
particle 
[.eta.].sub.P 
[.eta.].sub.T 
[.eta.].sub.EP 
content 
amount in 
particles 
1st step 
Melt Index 
State in 
No. 
(g) Size (.mu.m) 
.sigma.g 
(dl/g) 
(dl/g) 
(dl/g) 
(wt %) 
2nd step (wt %) 
(g/cm.sup.2) 
(wt %) 
(g/10 
autoclave 
__________________________________________________________________________ 
Ex. 2 
327 470 1.1 
1.52 
2.22 
3.7 16 32 2.4 2.1 3.4 No problem 
Ex. 3 
341 470 1.2 
1.46 
2.16 
3.3 16 38 2.6 1.9 3.2 No problem 
Ex. 4 
393 480 1.3 
1.48 
2.27 
3.4 18 41 3.1 1.9 2.9 No problem 
Ref. 
267 490 1.2 
1.51 
1.89 
3.6 8.3 18 6.0 3.2 7.6 Polymer 
Ex. 1 particles 
adhered 
Ref. 
300 490 1.3 
1.46 
1.90 
3.8 9.1 19 7.9 3.1 7.3 Polymer 
Ex. 2 particles 
aggregated 
Ref. 
275 500 1.2 
1.50 
2.01 
3.7 11 23 12.0 3.2 6.6 Polymer 
Ex. 3 particles 
aggregated 
Ref. 
413 530 1.9 
1.49 
2.29 
3.9 16 33 6.8 3.0 3.1 Polymer 
Ex. 4 particles 
adhered 
Ref. 
382 540 2.0 
1.49 
3.63 
8.2 15 32 5.1 3.2 0.2 Polymer 
Ex. 5 particles 
adhered 
Ex. 5 
340 520 1.5 
1.33 
2.36 
3.9 18 40 2.1 3.6 2.7 No 
__________________________________________________________________________ 
problem 
As shown in the above Examples and Reference Examples, the present 
invention can produce the desired .alpha.-olefin block copolymer having 
extremely excellent impact resistance at a low temperature and molding and 
processing characteristics, and also polymer particles having a narrow 
distribution of particles and a low adhesion force. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention, and all such modifications as 
would be obvious to one skilled in the art are intended to be included 
within the scope of the following claims.