Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
248
This invention relates to an impact-rosistant
chemically blended propylene polymer composition suitable
for production of molded articles having superior pro-
perties such as impact strength and rigidity and improved
whitening resistance and gloss, and to a process for pro-
ducing the composition.
: More specifically, the invention relates to a
process for preparin~ an impact-resistant chemically
blended propylene polymer composition, which comprises
form ng crystalline polypropylene composed substantially
of propylene and having an isotactic index of at least 90
in the presence of a catalyst composed of (a) a carrier-
supported titanium catalyst component containing at least
magnesium, halogen and titanium, preferably together with
an orga~ic carboxylic acid ester, on the surface of the
carrier and (b) an organoaluminum compound; formi~g a
low-crystalline propylene-rich propylene/ethylene copolymer
in the presence of the resulting product and the catalyst
in the same reaction zone or in a separate reaction zone;
and then forming polyethylene or an ethylene-rich ethylene/
propylene copolymer having an intrinsic viscosity of at
~ l~ast 0.5 but less than 206 in the presence of the reaction
: product of the second step and the catalyst in the same
reaction zone or in a separate reaction zone, thereby to
provide a chemically ble~ded polymer composition having
aa ethylene content of ~ to 40 mole%.
; The term "chemically blended polymer composition",
as used in the present application, means that the composi-
- tion is not a so-called polymer blend obtained by first
248
preparing different polymers or copolymers, and then
blendi~g them physically.
Although crystalline polypropylene produced by
using stereoregular catalysts have superior rigidity and
thermal stability, it suffers from low impact strength
particularly at low temperatures, and this disadvantage
limits its uses.
In an attempt to overcome the disadvantage,
suggestions were made heretofore to produce polymer com-
positions by mixing polypropylene with polyet~ylene or anethylene~propylene copolymer (for example, U~ S0 Patent
3,256,367, and Japanese Patent Publications Nos. 7345/66
and 22626/70). With physical blending means, however, it
is difficult to attain such a high degree of uniformity
in the mixing and dispersion of ingredients in the result-
ing polymer composition as can be done by a chemical means
of multi-step polymerization in accordance with the present
invention. Presumably for this reason, these prior methods
cannot avoid incident deterioration in the desirable pro-
perties of polypropylene itself although they do bringabout some improvement in the impact resistance of the
resulting polymer composition~ The mixing operation, too,
is complicated, and it is necessary first to prepare
polymers to be blended, and then melt-mix them by this
complicated operation using extra equipment.
Some suggestions were made, on the other hand,
to provide chemically blended polymer compositions by a
multi-step polymerization process in an attempt to overcome
these difficulties of the polymer blending methods. A first
`` il~2~8
suggestion is disclosed in Japanese Patent Publication No.
20621/~9 which relates to the production of a polymer
composition having improved impact strength at low tem-
peratures by forming a polymer composed substantially
of propylene or a propylene/ethylene copolymer, then
forming a propylene-rich propylene/ethylene copolymer, and
further forming an ethylene-rich ethylene/propylene co
- polymer, all the reactions being performed in the presence
of a stereoregular catalyst composed of (a) a titanium
trichloride composition obtained by reducing ~iC14 with
metallic aluminum and (b) an organoaluminum compound. In
order to achieve a further improvement, another suggestion
was later made (Japanese Patent Publication ~o~ 24593/74)
in which a polymer composition improved over the composi-
tion obtained in the first suggestion is prepared usingthe same catalyst as in the first suggestion by first form-
-~ ing polypropylene, then forming an ethylene-rich ethylene/
: propylene copolymer, and then forming an ethylene/propylene
: copolymer having a higher ethylene content. A third sug-
gestion, similar to the seco~d one, was also made (Japanese
Patent .Publication ~oO 30264/74) which involves using the
: same catalyst as in the first and second suggestions, and
first forming polypropylene in the presence of a chain-
transfer agent, then forming an ethylene-rich ethylene/
propylene copolymer, and finally forming polyethylene or
an ethylene/propylene copolymer having a higher e~hylene
1~ contentr A fourth .5uggestions, similar to the third, is
L.~ Ger~ o~ /eg~gssc~ r~ 4~ ~0
also known (D~-r~2,~17,093)~
None of these first to fourth suggestions disclose
.
` " 11~(~248
the utilization of a carrier-supported titanium catalyst component. The
second to fourth suggestions show that in order to obtain polymer compositions
having improved properties, it is important to form an ethylene-rich ethylene/
propylene copolymer in the second step instead of the propylene-rich ethylene/
propylene copolymer in the second step of the first suggestion.
German Offenlegungsschrift No. 2700774 ~laid open on August 25, 1977)
states that the chemically blended compositions in the prior art are still
unsatisfactory for providing molded articles having rigidity and impact
strength in a well balanced state, and disclosed, as an improvement, an
impact-resistant chemically blended propylene polymer composition having an
ethylene content of 3 to 40 mole% and comprising
-~ (A') 55 to 95% by weight of crystalline polypropylene containing
O to 1 mole% of another olefin and having an isotactic index of at least 90,
~ B') 1 to 10% by weight of a low-crystalline propylene/ethylene
copolymer containing 60 to &5 mole% of propylene, and
~ C') 1 to 35 mole% by weight of polyethylene or an ethylene/propy-
. lene copolymer containing up to 10 mole% of propylene which has an intrinsic
viscosity of at least 2.6, the total proportion of (A'), (B') and (C') being
100% by weight; and a process for preparing this composition
_5_
248
comprising three stepsO
In this suggestion, the polyethylene or ethylene/propylene copolymer (C') formed in the third step has an
intrinsic viscosity of at least 206, preferably at least ~,
especially 3 to 10~
~ he present inventors unexpectedly found that
the same chemically blended polymer composition containing
the aforesaid polyethylene or ethylene/propylene copolymer
except having an intrinsic viscosity of at least 0.5 but
less than 2.6 which range is excluded from the composition
of the prior suggestion has improved whitening resistance
and gloss in addition to good impact strength and rigidityO
~ he "whitening resistance", denotes the resistance
to whitening which occurs in a molded article upon the appli-
cation of an impact or upon bending at or near the partwhich has undergone the impact or has been bended~
It is an object of this invention therefore to
. provide an impact-resistant chemically blended propylene
polymer composition having the aforesaid improved properties,
and a process for preparing the composition.
Other objects and advantages of the invention will
become apparent from the following descriptionO
According to the process of this invention, a
chemically blended propylene polymer composition having a
high impact strength can be obtained by a chemical means
of multi-step polymerization consisting of the three steps
shown below~ Each of the steps needs not to be carried
out in one stage, but may be done in two or more stages.
: For example, an embodiment can be used in which the first
11C~$248
step is carried out in two stages, and followed by the
second and third steps each performed in one stageO
~irst st~p
Propylene containing 0 to 1 mol e% of another
olefin, preferably propylene alone, is polymerized in the
presence of a catalyst composed of (a) a carrier-supported
titanium catalyst component containing at least magnesium,
halogen and titanium on the surface of the carrier and (b)
an organoaluminum compound to form crystalline polypropylene
having an isotactic index of at least 90 which accounts for
:~ 55 to 9y/o by weight, preferably 60 to 90/O by weight, of the
final polymer compositionO
Second ste~
: Propylene and ethylene are polymerized in the
presence of the reaction product of the first step and the
same catalyst while maintaining the content of propylene
in the gaseous phase of the polymerization zone at 65 to
90 mole%, preferably 70 to 85 mole/0, thereby to form a low-
crystalline propylene/ethylene copolymer having a propylene
content of 60 to 85 mole%, preferably 60 to 80 mole/0, which
accounts for 1 to 10% by weight9 preferably 2 to 8% by
weight, of the final polymer compositionO
~hird_steP
Ethylene, or both ethylene and propylene are
polymerized in the presence of the reaction product of the
second step and the same catalyst while maintaining the
content of propylene in the gaseous phase of the polymeriza-
tion zone at 0 to 7 mole/~, preferably 0 to 4 mole/0, thereby
to for.m polyethylene or an ethylene/propylene copolymer
248
having a propylene content of up to 7 mole%, preferably
up to 3 mole/O~ espeGially up to 2 mole%, which has an
intrinsic viscosity of at least 005 but less than 206,
preferably at least 005 but not exceeding 2.3, and accounts
for 1 to 35% by weight, preferably 5 to 3~/0 by weight, of
the final polymer compositionO
In these steps, the reactions are carried out so
that the final polymer composition has an ethylene content
of 3 to 40 mole/0, preferably 10 to 35 mole,~0
10 ~he combination of the following elements, i.eO,
(i) the reactions for forming polymer composition
are carried out in the presence of a catalyst composed of a
. carrier-supported titanium catalyst component containing at
least magnesium, halogen and titanium on the surface of the
; 15 carrier and an organoaluminum compound;
- (ii) in the second step, propylene is polymerized
- with ethylene using the propylene in excess to form a
propylene-rich propylene/ethylene copolymer having a speci-
fied amount of propylene; and
(iii) polyethylene or an eth~lene-rich ethylene/
propylene copolymer having an intrinsic viscosity of at-
least 005 but less than 20 6 is formed in the third step,
is important~ in combination with the other conditions
specified in the first to third steps, to achieve the
objects of this inventionO For example, if a propylene/
ethylene copolymer having the specified propylene content
is formed in the second step but the product of the third
step does not have the specified viscosity, the improvement
~ achieved b~ the present invention cannot be expectedO
.~ - 8 -
248
~hus, according to this invention, there is
provided a chemically blended propylene polymer composi-
tion having impact strength, said composition comprising
(A) 55 to 95% by weight, preferably 60 to 90%
by weight, of crystalline polypropylene having another
olefin content of 0 to 1 mole/0 and an isotactic index of
at least 90,
(B) 1 to 10 % by weight, preferably 2 to 8% by
weight, of a low-crystalline propylene/ethylene copolymer
having a propylene content of 60 to 85 mole%, preferably
60 to 80 mole%, and
. (C) 1 to 35% by weight, preferably 5 to 30% by
weight, of polyethylene or an ethylene/propylene copolymer
having a propylene content of 0 to 7 mole% and an intrinsic
viscosity of at least 0O5 but less than 206, preferably at
least 0O5 but not exceeding 2O3;
and having an eth-~lene content of 3 to 40 mole/0, preferably
10 to ~5 mole%, the total amount of the constituents (A),
(B) and (C) being 100% by weightO
In the present invention, the intrinsic viscosity
(~) of polymers is calculated in accordance with the follow-
ing equation
g ( sp/c) = log ~7) + 0O18 (~)
in which the specific viscosity is measured on a decalin
solution at 135C using a Fitz-Simons viscometer~
The isotactic index denotes the content in
weight % of a boiling n-hepta~e-insoluble portion of
- polymer which is measured by the method to be described
hereinbelowO
_ g _
110~248
Tlle production of the chemically blended impact-
resistant propylene polymer composition of this invention
is described in greater detail hereinbelowO
~he polymer composition of the invention is
. 5 obtained by polymerizing or copolymerizing olefins in a
series of polymerization systems using a carrier-supported
stereoregular catalyst, and in the resulting polymer com-
position, the individual components are dispersed and mixed
in and with one another homogeneouslyO Physically blended
polymer compositions obtained by producing starting polymers
or copolymers and then mixing them by physical means are
outside the scope of the present invention, as stated here-
: inaboveO The improvement in accordance with this invention
- cannot be achieved by the physically blended polymer com-
positions because the properties of polymer compositions
are greatly affected by the types and proportions of the
constituent po].ymers or copolymers and the dispersed state
of the constituents, and no physical means can achieve
such a high degree of uniformity in dispersed state as
chemical means canO
In the present invention, the three steps can
be carried out in the same zone or in two or more zones,
but preferably, each of these steps is carried out in a
: separate reaction zoneO ~urthermore, in the process of
i 25 this invention, the reactions are continued in the presence
of the catalyst and the reaction product of the previous
step without deactivating the catalyst until the final
polymer composition is obtainedO As required, a fresh
supply of catalyst is added in any desired stepO Each of
:
-- 10 --
~ )Q2~8
the steps may be carried out in a plurality of stages, and in this
case, the final polymer or copolymer obtained after such stages in a
step should meet the requirements specified hereinabove. For example,
the third step may be operated such that polyethylene or an ethylene/
propylene copolymer having a propylene content of not more than 7
mole % is formed in two or more reaction zones to provide a product
having an intrinsic viscosity of at least 0.5 but less than 2.6 on an
average.
The catalyst used in the first to third steps is composed of
a carrier-supported catalyst component containing at least magnesium,
halogen and titanium on the surface of the carrier, and an organoalum-
inum compound. The carrier-supported catalyst component may be any
which contains at least magnesium, halogen and titanium on the surface
of the carrier, and which, if desired, has been treated with a donor
and/or an active hydrogen-containing compound. Preferably, the
carrier-supported titanium catalyst component is treated with an
organic carboxylic acid ester, particularly an aromatic carboxylic acid
ester. In other words, it is convenient to use a carrier-supported
titanium catalyst component containing at least magnesium, halogen
and titanium on the surface of the carrier and treated with an
organic carboxylic acid ester, particularly an aromatic carboxylic
acid ester.
A number of prior suggestions have been known in regard
to the preparation of such a carrier-supported titanium catalyst
composition (see, for example, Deutsches Patentsschrift No.
2,153,520, Deutsches Patentsschrift No. 2,230,672, Deutsches
Patentsschrift No. 2,230,728, Deutsches Patentsschrift No.
2,230,752
110~248
Deutsches Patentsschrift No. 2,504,036, Netherlands laid-open Patent
Publication No. 75.10394, Deutsches Patentsschrift No. 2,605,922, and
Japanese Laid-Open Patent Publications Nos. 126590/74 and 57789/76).
Several embodiments of producing the carrier-supported titanium
catalyst component containing at least magnesium, halogen and titanium
on the surface of the carrier and treated with an organic carboxylic
acid ester which is especially suitable for use in the process of
` this invention are given below.
(1) A magnesium halide, preferably magnesium chloride or
magnesium bromide, and an organic carboxylic acid, preferably an
aromatic carboxylic acid ester, are mechanically pulverized in the
absence or presence of a small amount of a liquid inert diluent,
a silicon compound, or an aluminum compound, and the pulverized
product is reacted with a titanium halide, preferably titanium
tetrachloride with or without treatment with an organoaluminum
compound.
:: (2) An organic complex between magnesium and aluminum
or silicon which contains a halogen atom and an alkoxy group is
reacted with an organic carboxylic acid ester, preferably an aro-
matic carboxylic acid ester, and the reaction product is further
reacted with a titanium compound, preferably titanium tetrachloride.
(3) The product obtained in (1) and (2) is further
; reacted with a~l organic carboxylic acid ester, preferably
an aromatic carboxylic acid ester, and a titanium compound,
preferably titanium tetrachloride.
(4) The product obtained in (1) or ( 2 ) is further
reacted with an organic carboxylic acid ester, preferably
:
:'
- 12 -
, .
248
an aromatic carboxylic acid ester, a titanium compound,
preferably titanium tetrachloride, and an organoaluminum
compound~
Titanium i.n the titanium complex produced by using
titaniu~ tetrachloride in the embodiments (1), (2) and (3)
above is tetravalent in most casesO When titanium tetra-
chloride is used in method (4), titanium in the titanium
complex is in most cases a mixture of tetravalent titanium
and trivalent titanium, although it may differ according to
the amount of the organoaluminum compound to be reactedO
~ he organic carbox~lic acid ester used in the
above embodiments may, for examæle, be (i) aliphatic carbo-
xylic acid esters and halogenated aliph&tic carboxylic acid
esters, or (ii) aromatic ca.rboxyllc acid estersO
Aliphatic carboxy].ic acid esters or halogenated
aliphatic carboxylic acid esters (i) usually employed are
esters formed between saturated or unsaturated aliphatic
carboxylic acids containing 1 to 8 carbon atoms, preferably
1 to 4 carbon atoms, or halogen-substituted products thereof,
and saturated or unsaturated aliphatic prinary alcohols con~
taining 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms,
saturated or unsaturated alicyclic alcohols containing 3 to
8 carbon atoms, preferably 5 or 6 carbon atom, phenols con-
taining 6 to 10 carbon atoms, preferably 6 to 8 carbons, or
aliphatic saturated or unsaturated primary alochols contain-
ing 1 to 4 carbon atoms bonded to alicyclic or aromatic
rings containing 3 to 10 carbon atoms~
Aromatic carboxylic acid esters (ii) generally
employed are esters formed between aromatic carboxylic acids
~10(~248
eontaining 7 to 12 carbon atoms, preferably 7 to 10 carbon
atoms, and saturated or un.saturated aliphatic primary alcohols
eontaining 1 to 8 carbon atoms, preferably 1 to 4 carbon
- atoms, phenols containing 3 to 8 carbon atoms, preferably
. 5 6 to $ carbon atoms, or aliphatic saturated or unsaturated
primary alcohols containing 1 to 4 carbon atoms bonded to
alicyclic or aromatic rin~s containing 3 to 10 carbon atomsO
Specific examples of the aliphatic carboxylic
aeid esters (i) include alkyl esters of saturated fatty
acids such as methyl formate, ethyl acetate, n-amyl acetate,
2-ethylhexyl acetate, n-butyl formate, ethyl butyrate or
ethyl valerate7 alkenyl esters of saturated fatty acids such
as vinyl aeetate or allyl acetate; and primary alkyl esters
of unsaturated fatty acids as methyl acrylate, methyl meth-
aerylate or n-butyl crotonateO
: Specific examples of the aromatic carboxylic acid
- esters (ii) are alkyl esters of benzoic acid such as methyl
benzoate, ethyl benzoate, n-propyl benzoate, n- or i-butyl
benzoate, n- or i-amyl benzoate, n-hexyl benzoate, n-octyl
benzoate or 2-ethylhexyl benzoate; alkyl esters of toluic
~ aeid such as methyl toluate, ethyl toluate, n- or i-butyl
toluate, or 2-ethylhexyl toluate; alkyl esters of anisie
aeid sueh as methyl anisate, ethyl anisate or n-propyl
: anisate; and primary alkyl esters of naphthoic acid such
25 as methyl naphthoate, n-propyl naphtoate, n-butyl naphthoate,
. or 2-ethylhexyl naphtoateO
~he aromatic carboxylic acid esters are preferred
; among themO Especially preferred aromatic carbo~ylic
acid esters are Cl 8 alkyl esters of monocyclic aromatic
, .
- 14 _
'
248
`~ carboxylic acids such as methyl benzoate~ ethyl benzoate,
methyl p-toluate, ethyl p~toluate, methyl p-anisate, and
ethyl p-anisateO
~he li~uid inert diluent used in the above embodi-
ments may include, for example, hydrocarbons, halogenatedhydrocarbons and carbon halides which are liquid at room
temperatureO Specific examples include aliphatic hydro-
carbons such as n-pentane, iso-pentane, n-hexane, iso-
hexane, n-heptane, n-octane, 2-ethylhexane, n-decane, and
kerosene; alicyclic hydrocarbons such as cyclopentane,
cyclohexane, and methyl cyclohexane; aromatic hydrocarbons
such as benzene, toluene, xylene, ethylbenzene, cumene,
cymene, mesitylene, pseudocumene, and butylbenzene; halo-
genated hydrocarbons such as methylene chloride, ethyl
chloride, ethylene chloride, trich]oroethylene, chloro-
benzene, n-propyl chloride, iso-propyl chloride and chlore-
form, and carbon halides such as carbon tetrachlorideO
~ he organoaluminum compound used in the above
embodiments include, for example, compounds of the formula
R'3 mAlXm wherein R' is a hydrogen atom, or an alkyl or
aryl group, X is a halogen atom~ and m is O or a positive
number of less than 3, compounds of the formula R'3 nAl(OR)n
wherein R is an alkyl or aryl group, R' is as defined above,
and n is a positive number greater than O but less than 3,
and comp~unds of the formula RAl(OR)X wherein R and X are
as defined aboveO Examples are trialkyl aluminums, alkyl
aluminum halides, alkyl aluminum hydrides, and alkyl aluminum
. alkoxidesO
Specific examples, are triethyl aluminum, diethyl
24~3
aluminum hydride, tripropyl aluminum, tributyl aluminum,
diethyl aluminum chloride, diethyl aluminum bromide, diethyl
aluminum ethoxide, diethyl aluminum phenoxide, ethyl aluminum
ethoxychloride, ethyl aluminum sesquichloride, diethyl
aluminum ethoxide and ethyl aluminum diethoxideO
In the process of this invention, the reactions
for forming the desired polymer compositions are carried
. out in the presence of the catalyst described hereinabove
- which is composed of a carrier-supported titanium catalyst
component containing at least magnesium, halogen and titanium
on the surface of the carrier and an organoaluminum compoundO
~ ~xamples of the organoaluminum compound used in
: preparing this catalyst are trialkyl aluminums or dialkyl
. aluminum halides containing an alkyl group with 1 to 12
carbon atomsc ~he use of the trialkyl aluminums is pre-
ferredO Examples of suitable organoaluminum compounds
include (C2H5)Al, (i-C4H9)3Al, (n-C4E9)3Al, ~CH3CH(CH3)
CH2CH2CH3)3A1~ (Cl2H25)3Al and (C2H5)2 2 5 2
~he process of this invention may be performed
~ ~ 20 in the presence of an organic carboxylic acid ester, pre-
~ ferably an aromatic carboxylic acid ester~ The same esters
. ; as exemplified hereinabove with regard to the production
of the carrier-supported titanium catalyst component can
be used as the organic carboxylic acid esters for this
purposeO ~hese esters serve to increase the proportion of
` a highly stereoregular polymer formed, when the polymeriza-
tion is carried out in the presence of hydrogen as a chain-
transfer agentO ~he introduction of the carrier-supported
- titanium catalyst component, the organoaluminum compound
- 16 -
1~0~248
catalyst component, and the organic carboxylic acid ester
into the reaction zones and the mixing of them may be
performed in any desired sequenceO ~he amount of the free
organic carboxylic acid ester used is, for examp]e, not
more than about 1 mole, preferably about OoOl to about 0O5
moleg per aluminum atom of the organoaluminum compound in
the catalystO
In the process of this invention, the first step
of forming crystalline polypropylene having an isotactic
index of at least 90 is carried out in the presence of the
aforementioned catalyst using propylene which may contain
up to about 1 mole/0 of ethyleneO The polymerization is
carried out at a temperature of from room temperature to
about 100C, preferably about 20 to about 80C, more pre-
ferably about 30to about 80C and a pressure of fromatmospheric pressure to about 30 kg/cm2, preferably from
atmospheric pressure to about 20 kg~cm2O Yreferably, the
reaction is carried out in an inert hydrocarbon solvent
such as pentane, hexane, heptane or keroEeneO The preferred
concentration of the catalyst is such that the amount of the
titanium catalyst component is about OoOl to about 10 millimole/
liter calculated as the titanium atom, and the amount of
the organoaluminum compound is about OoOl to about 30
millimoles/liter, both based on the volume of the solventO
Hydrogen is most preferred as a chain transfer agentO The
use of chain transfer agents is not essential, howeverO ~he
amount of hydrogen as a chain transfer agent is up to about
20 mole% based on the monomers fed to the polymerization
vesselO
- 17 -
248
The purpose of the first-step polymerization is
to provide crystalline polypropylene having superior
rigidity, and it is preferred therefore, to polymerize
propylene aloneO However, a minor amount9 for example,
up to about 1 mole~, of another olefin such as ethylene
may be present togetherO ~he first-step polymerization
is effected so as to provide crystalline polypropylene
having an isotactic index of at least 90 which accounts
for about 55 to about 95% by weight, preferably about 60
to 90% by weight, of the final polymer compositionO The
isotactic index is determined as follows:
~ he polymer is recovered from the slurry after
polymerization, and driedO ~he resulting powdery polymer
is extracted for 6 hours with n-heptane using a Soxhlet
extractorD ~he isotactic index of the polymer is defined
as the percentage of the weight of the residue of polymer
after extraction to the weight of the polymer before
-; extractionO
~he second step of forming a low-crystalline
propylene-rich propylene/ethylene copolymer in the process
of this invention is carried out in the presence of both
- the reaction product of the first step and the aforementioned
catalystO Preferably, prior to the polymerization in the
second step, the monomer~, or both the monomers and hydrogen,
remaining at the end of the first step are removed by flush-
. ing, and then a mixture of ethylene and propylene is intro-
duced and polymerized while maintaining the propylene content
in the gaseous phase of the polymerization zone at 65 to
90 mole%O If desired~ an alternative procedure may be
: - ~8 -
11~)(~248
employed in which the unreacted monomers are left partly
or wholly, and ethylene or both ethylene and propylene
are introduced into the polymerization zone to adjUEt
the monomer composition as specified aboveO
The second step is carried out so as to provide
a propylene-rich propylene/ethylene having a propylene
content of 60 to 85 mole/O~ preferably ~ to ~0 mole~O~ which
accounts for 1 to l~/o by weight, preferably about 2 to about
~0 by weight, of the final polymer compositionO In order
to obtain a copolymer of this composition, the propylene
content of the gaseous phase of the polymerization zone is
adjusted to 65-90 mole%, preferably 70-85 mole/OO
Since there is some difference in copolymerizability
between ethylene and propylene depending upon the catalyst
system used, it is desirable to perform a preliminary ex-
periment of copolymerization in order to pre-determine the
monomer composition of the gaseous phase in the polymeriza-
tion zoneO
The second-step polymeri.æation may be carried out
in the absence or presence of hydrogen as a chain transfer
agentO In view of the properties of the final polymer com-
position, it is preferred to perform the above copolymeriza-
tion in the substantial absence of hydrogen to form a
propylene-rich propylene/ethylene copolymer having a rela-
tively high molecular weightO Other polymerization condi-
tions are preferably the same as in the first stepO
In the second step, homopolymers of ethylene and
propylene may form in small amounts together with the
ethylene/propylene copolymerO The purpose of the second
.
248
step is to form a low-crystalline propylene-ri.ch propylene/
ethylene copolymer, and this purpose can be achieved by
forming the polymer in an amount of 1 to 40/0 by weight based
on the weight of the polymer produced in the first stepO
'~he third step of forming polyethylene or an
. ethylene-rich ethylene/propylene copolymer having a propylene
content of up to 7 mole/0 and an i.ntrinsic viscosity of at least
-- 005 but less than 206 is carried out in the presence of the
. reaction product of the second step and the catalystO In
. 10 this polymerization, ethylene alone, or a mixture of propylene
and ethylene, is polymerized while maintaining the propylene
content of the gaseous phase of the polymerization zone at
- up to 7 mole%, preferably ~p to 4 mole% (that is, the ethylene
: content is at least 93 mole%, preferably at least 96 mole/0)O
.; 15 Prior to the polymerization in the third step, the
unreacted monomers in the second step may be removed; or
. they are left unremoved and the monomer composition is ad-
~ justed to the aforementioned rangeO '~he polymerization is
;- carried out in the presence or absence of a chain transfer
. 20 agentO It is necessary to adjust the intrinsic viscosity
~ of the polymer formed in the third step to at least 0.5 but
.. : less than 206, preferably at least 005 but not exceeding
20~ he third step is performed so as to afford the polymer
or copolymer which accounts for 1 to 35% by weight, prefer-
:~ 25 ably 3 to 30% by weight, of the final polymer compositionO
~y the procedure mentioned above, a polymer com-
~ position having an ethylene content of 3 to 40 mole%,
preferably about 5 to about 35 mole%, is formed as a final
product~
- 20 -
248
The composition and amount of the polymer in each
step can be easily controlled by properly .selecting polymer-
ization conditions such as the polymerization temperature,
the concentrations of the catalyst components, the concentra-
tion of monomers, the monomer composition, the concentration
of chain transfer agent7 the pressures of monomers, and the
residence timeO The intrinsic viscosity of the product
obtained in the third step can be easily calcul.ated in
accordance with the following equation once the intrinsic
viscosities of the polymers obtained in the first and second
steps are measuredO
~)final ~ ~ Ci(~)i
~)final is the intrinsic viscosity of
: the final polymer composition; Ci is the per-
centage of the weight of the polymer fomred in
a step whose position in a series of steps is
indicated by an ordinal number i to the weight
of the entire polymer; and (~)i is the intrinsic
viscosity ~) of the polymer formed in the step
indicated by the ordinal number 1O
~hus7 by measuring the amounts and intrinsic
viscosities of the polymers withdrawn before the final
step, the intrinsic viscosity of the polymer formed in
the third step can be calculatedO
Since the polymer co~position obtained by this
invention is formed by a chemical means in a series of
polymerization reaction systems, the constituents of the
composition are far more uniformly dispersed and mixed
.
- 21 -
248
than a mechanical blend of polymers obtained, and the
composition of the invention has properties not obtain-
able by the mechanical blendO The use of the specific
carrier~supported titani.um catalyst component contributes
to the homogeneously dispersed state of the constituent
polymers in the polymer composition of this inventionO
The polymer obtained in each step has some distribution
in composition9 and the chemically blended product obtained
by the three steps, on an average, becomes a final polymer
composition composed of tlle components (A), (B) and (C) in
~ the proportions specified aboveO
: The polymer components (A), (B) and (C) in the
~ final chemically blended polymer composition formed by the
: process of this invention can be fractionated by the follow-
. 15 ing methods, and their proportions can be determined
accordinglyO
(1) The final composition is dissolved in re-
fined kerosene heated at 150C, and then the solution is
cooled to room temperatureO Thus~ the composition is
separated into a fraction soluble in ~erosene and a frac-
tion insoluble in ito The fraction soluble in kerosene
corresponds to component (B) in the final composition of
this inventionO
(2) The fraction insoluble i.n kerosene obtained
by procedure (1) is further extracted with kerosene at 110C~
The polymer obtained as a fraction insoluble in kerosene at
110C by this procedure is high-molecular-weight polypro-
pylene or propylene-rich propylene/ethylene polymerO
(~) The polymer obtained as a fraction soluble
116)~Z48
in kerosene at 110C by the above procedure (2) is extracted
under heat with a mixture of kerosene and butyl carbitol to
separate it into polyethylene or ethylene-rich ethylene/
propylene copolymer as an insoluble fraction~ and low-
molecular-weight polypropylene or propylene-rich propylene/
ethylene copolymer as a soluble fraction.
(4) The sum of the fraction insoluble in kerosene
at 110C obtained by procedure (2) and the fraction soluble
in the mixed solvent by procedure (3) correspond.s to com-
ponent (A) in the final polymer composi.tion of this inventionO
~he molar ratio between ethylene and propylene
in each polymer can be determined in a customary manner by
a melting infrared spectroscopic method and an NMR spectro-
scopic methodO
~he following Examples and Comparative Examples
illustrate the present inventi.on in more detailO
Example_l
reparation of a~titanium ~catalyst component
One kilogram of commercially available anhydrous
magnesium chloride, 002~ liter of ethyl benzoate and 0015
- liter of meth-~l polysiloxane (viscosity 20 centipoises at
25C) were fed in an atmosphere of nitrogen into a stainless
steel (SUS 32) vibratory ball mill accommodating therein
35 kg of stainless steel balls, and pulverized at 708 G
for 80 hoursO The solid product of the pulverization
treatment was suspended in 10 liters of titanium tetra-
chloride, and contacted with stirring at 80C for 2 hoursO
~he solid product was collected by filtration, and washed
with purified hexane until no titanium was detected in the
1~ 8
wa~sh liquidO Drying of the product afforded a titanium-
containing solid catalyst component which contained 20 0%
by weight oî titanium as atom, 6500% by weight of chlorine
- as atom and 800% by weight of ethyl benzoate.
Pre~aration of a polymer composition
The apparatus used consisted of three polymeriza-
tion reactors A, B and C having a capacity of 18, 18, and
25 liters respectively and connected in series and a flush
tank D (capac-ity 3 liters) disposed between polymerization
reactors B and CO Reactor A was charged with 00079 millimole/
hr, calculated as titanium atom, of the titanium catalyst
component pre~ared as described in the previous paragraph
-. as a hexane slurry, 3~95 millimole.s/hr of triethyl aluminum
as a hexane solution, and lo 49 millimoles/hr OI methyl p-
toluate as a hexane solution, with the total rate of the
; hexane fed being 2010 liters/hrO Propylene was fed con-
: tinuously at a rate of 00 714 ~3/hr, and hydrogen was added
at a rate of 108 ~/hr so that the concentration of hydrogen
in the gaseous phase became 30 5 mole%O Propylene was thus
polymerized at 60Co ~he pressure of the inside of reactor
A at this time was 7 o 2 kg/cm2oGO
In reactor A, polypropylene having a melt index
(measured at 190C under a load of 216 kg) of 4083 and an
: isotactic index of 920 5 (as a result of extraction with
n-heptane) was formed at a rate of 989 g/hrO
~he slurry discharged from reactor A was fed into
reactor B, and 4000 ~R/hr of propylene, 5804 ~/hr of
ethylene and 3 liters/hr of hexane were fed into reactor Bo
~hus, propylene and ethylene were copolymerizedO ~he pressure
- 24 -
llO~Z48
of the inside of reaGtor B was 2.0 kg~cm2G~ and the
propylene content of the monomeric mixture in the gaseous
phase was 840 7~ mole/0O A copolymer was obtained at a rate
of 292 g/hl in reactor Bo
Subsequently, the .slurry from reactor B was
conducted to flush tank D to remove the unreacted monomers
and hydrogen, and then introduced into reactor CO Ethylene
was fed into reactor C at a rate of ~0604 N~/hr, and hydrogen
was added so that the hydrogen content in the gaseous phase
became 4508 mole% (nitrogen 705%)0 :Ethylene was thus
polymerized in reactor CO ~he polymerization pressure in
reactor C was lo 5 kg/cm2oG~ and the amount of the polymer
formed was 409 g/hrO
By pressure reduction, the unreacted monomer and
hydrogen were removed from the effluent that came from
. reactor CO The resulting polymer was separated by filtra-
tion, and dried to afford a white powdery polymer composition
at a rate of 1,511 g/hrO ~he polymer composition had a
. melt index of ~02 and an intrinsic viscositv of 20 580 ~he
ethylene content of the polymer composition was ~502 mole%O
~he polymer formed in reactor C had an intrinsic
viscosity of 10800
A part of the polymer composition was dissolved
in Xerosene at 150C~ and cooled to room temperatureO The
polymer precipitated was separatedO An amorphous polymer
containing 67 mole~O of propylene was obtained from the
kerosene solutionO ~he proportion of the amorphous polymer
was 4085% by weight based on the polymer compositionO
An antioxidant was added to the polymer composition,
: - 25 -
. , .
` 110~248
and test pieces were prepared from the mixturec The pro-
: perties of the test pieces were measured, and the results
are shown in Table lo
The properties of the polymer composition were
., 5 determined by the following methodsO
Tensile ctress at_y~eld~Qint
In accordance with ASTM D638-64To ~he test pieces
were prepared according to new JIS K-71130 The pulling
speed was 50 mm~minO
: 10 E]on~ation at br,e~ak
Same as the tensile stress at yiel,d pointO
Izod im~act stren~th
In accordance with ASTM D256-560 ~otchedO 230CD
Gloss,
In accordance with ASTM D5230 Incidence angle 20Co
Whitening
A weight (R=l/2 inch) of a specified shape was let
fall from a height of 50 cm onto a specified test piece
(120 x 130 x 2 mm), and the degree of whitening was evaluated
visuallyO The results was rated on the following scaleO
A: No change took placeO
B: A pale white pattern with a diameter of about
1 cm formedO
C: A white pattern with a diameter of about 2
to 3 cm formedO
_xample 2
The appratus used consisted of three polymeriza-
tion reactors A, B and C each having a capacity of 18 liters
and connected in series and a flush tank D (with a capacity
', 30 of 3 liters) disposed between reactors B and CO
- 26-
Z48
Reactor A was charged with 00079 millimole/hr,
calculated as titanium atom, of the titanium catalyst
component prepared in Examr)le 1 as a hexane slurry, 4023
millimole/hr of meth;yl p-toluate as a hexane solution, and
11085 millimoles/hr of triethyl aluminum as a hexane solu-
tion, with the total rate of hexane fed being 201 liters/hrO
~: Propylene and hydrogen were continuously introduced into
reactor A at a rate of 00717 NM3/hr and 302 N~/hr, respec-
tivelyO- The polymeri%ation temperature was 60C, and the
pressure of the inside of reactor A was 7 kg/cm2G0
In reactor A, polypropylene having a melt index
of 1404 and an isotactic index of 9105 was formed at a rate
of 1,025 g~hrO
The polymer slurry discharged from reactor A was
fed into reactor Bo Ethylene was introduced into reactor B
at a rate of ~502 N.~/hr, and hexane, at a rate of 3 liters/
hrO Thus~ ethylene and propylene were copolymerizedO The
pressure in reactor B was 106 kg/cm2oG, and the propylene
content of the monomeric mixture in the gaseous phase was
8507 mole%0
In re~ctor B, a polymer was formed at a rate of
198 g/hrO The polymer formed in reactor ~3 had an intrinsic
viscosity of ~io29_
Subsequently, the polymer slurry discharged from
reactor B was conducted to flush tank D~ and after removing
the unreacted monomers and hydrogen, ethylene was fed into
it at a rate of 19706 Nr/hro The ethylene content of the
monomeric mixture in the gaseous phase was 9708 mole%0
Hydrogen was added so that its amount became 2206 mole%
-- 27 --
`\
248
(nitrogen 420~) based on the gaseous phaseO Polymeriza-
tion was performed at 2.5 kg/cm2oGD In reactor C, an
ethylene polymer having an intrinsic viscosity of 1043 was
obtained at a rate of 266 g~hrO
~he effluent from reactor C was treated in the
same way as in Example 1 to afford a polymer composition
having a melt index of 8088 and an ethylene content of
2609 mole~0 at a rate of 1,377 g/hrO
The polymer composition was extracted with kerosene
in the same manner as in Example 1., and was found to contain
400/0 by weight of an amorphous ethylene-propylene copolymer
having a propylene content of 68 mole%0
~he properties of the resulting polymer composi-
tion were measured in the same way as in Example lo The
.~ 15 results are shown in ~abl.e lo
; xample ~
~he apparatus used consisted of three polymeriza-
tion reactors A, B and C (having a capacity of 18, 18~ and
25 liters, respectively) connected in series, and a flush
tank D (capacity 3 liters) disposed between reactors B and C0
Reactor A was charged with 90079 millimole/hr,
calculated as titanium atom, of the titanium catalyst com-
ponent prepared in Example 1 as a hexane slurry, 3095
millimoles/hr of triethyl aluminum as a hexane solution and
25 1049 millimoles/hr of meth~l p-toluate as a hexane solution,
with the total rate of hexane fed being 2D 1 liters/hrO
Propylene and hydrogen were cont;.nuously fed at
a rate of 0071~ ~M~/hr and 103 N~/hr, respectively, and
propylene was polymerizedO ~he pressure of the inside of
~ 28 ~
. .
Z48
reactor A at this ti.me was 700 ~g/cm2oG0
Polypropylene having an isotactic index of 9300
was formed at a rate of 986 g/hr i.n reactor A~
~ The polymer slurry discharged from reactor A was
- 5 introduced into reactor Bo Ethvlene and propylene were
fed into reactor B at a rate of 5804 ~P./hr and 4000 N/hr9
respectivelyO Thus~ ethylene and propyl.ene were copoly-
merizedO The propylene content of the monomeric mixture
in the gaseous phase of reactor B was 840~ mole%0
A polymer was formed at a rate of 278 g/hr in
reactor Bo
The polymer slurry discharged from reactor B was
introduced into flush tank D, and after removing the un-
reacted propylene, introduced into reactor C0 Ethylene was
fed at a rate of 132 ~/hr into reactor C, and polymerizedO
The amount of hydrogen i~ reactor C was adjusted
to ~04 mole% (nitrogen 1908%) based on the gaseous phaseO
The ethylene polymer formed i.n reactor C had an
intrinsic viscosity of 0090
The effluent from reactor C was treated in the
same way as in Example 1 to afford a polymer composition
at a rate of 1,281 g/hrO The composition had an ethylene
content of 2100 mole%0
The resulting polymer composition was extracted
with kerosene in the same way as in Example lo It was thus
found that the polymer composition contained ~o72~O by weight
of a non-crystalline copolymer of ethylene and propylene
with a propylene content of 67 mole%0
: The properties of the polymer composition were
- 29 -
1~ 248
measured in the same way as in Example lo The results
are shown in Table lo
Table 1
. . ~ ., . ~ .
__ _ . _ .. , ~ _ . . .... , ... ~.. __~ . _ .. ~ ~ , _ _ _ ,_ ____ . , _, _
~ensile
stress Elonga-
at yield tion at Izod impact
point break strength Gloss Degree of
Example (kg/cm2) (%) (kgcm/cm2) (%) whitening
_~ _.__ __ ..... __.,._............ ._. _. _, _.. ~ __. _ ~
] 264 803480 2/250 3 750 3 h
2 295 530 4~8/30 3 7100 A
.. z 275 803460 6/801 720 8 A
Comparative Example 1
~his comparison shows that the intrinsic viscosity
of the ethylene polymer in the polymer composition markedly
affects the gloss of the polymer compositionO
In Example 1, the polymer slurry discharged from
reactor B was conducted to flush tank D, and after removing
:~ the unreacted monomers, conducted to reactor C0 Ethylene
was fed into reactor C at a rate of 21600 NP/hr, and poly-
merized while introducing hydrogen so that the concentration
of hydrogen became 150 5 mole% (nitrogen 3209yo) in the gase-
ous phase~
: After the polymerization~ the polymer slurry was
treated in the same way as in ~xample 1 to afford a polymer
composition having an ethylene content of 310 5 mole/0 and an
intrinsic viscosity of 30060 Extraction of the composition
with kerosene showed that the polymer composition contained
- 3 -
` ~10~248
4044yO by weight of an amorphous copolymer with a propylene
content of 67 mole~0O
The ethylene polymer obtained in reactor C had
an intrinsic viscosity of 40480
'l'he result ng polymer composition had a gloss of
170 5% and a degree of whi.tening of Ao
Comparative Example 2
The apparatus used consisted of four polymeriza-
tion reactors A, B, C and E connected in series, and flush
tank D disposed between reactors C and Eo
Polymerization was carried out under the following
conditions O
~eactor A (19 liters) was charged with 00087
millimole~/hr, calculated as titaniwn atom, of the titanium
catalyst component prepared in :Example 1 as a hexane slurry,
13005 milli.moles/hr of triethyl aluminum as a hexane solu-
tion and 5022 millimoles/hr of methyl p-toluate as a hexane
solution, with the total rate of hexane fed being 201 liters/
hrO Propylene and hydrogen were fed at a rate of 864 N).7/hr
and 206 N~./hr, respectively, and propylene was polymerized
at 60Co The pressure in reactor A was lOoO l~g/cm2oG0
The polymer slurry discharged from reactor A was
conducted to reactor B (18 liters), and propylene was further
polymerized at a total pressure of 603 l~g/cm2GO In reactors
A and B, polypropylene having an isotactic index of 9005 was
formed at a rate of 1 t 259 g/hrO
The polymer slurry from rea(tor B was conducted
to reactor C (25 liters)0
~thylene and propylene were fed into reactor C at
)Z48
a rate of 10702 N/hr and 1607 N~/hr respectively, and
copolymerizedO ~he propylene content of the monomeric
mixture in the gaseous phase in reactor C was 62u 8%o
A polymer was formed at a rate of 268 g/hr in
reactor C0
~he polymer slurry from reactor C was co~ducted to
flush tank D (3 liters), and after removing a part of the
unreacted monomers, conducted to reactor E (18 liters)0
Ethylene was fed at a rate of 10506 N~/hr, and polymerizedO
- 10 When the concentrations of hydrogen, nitrogen~
ethylene and propylene in reactor E were adjusted to 1D1
mol e/O~ 460 9 mole%, 20 0 7 mole/0, and 2 0 6 mol e~O respectively
based on the gaseous phase~ an ethylene-propylene copolymer
having an intrinsi.c viscosity of 1064 was formed in reactor Eo
~he polymer slurry discharged from reactor E was
treated in the same way as in Example 1 to afford a polymer
composition having an ethylene content of 1502 mole%, a melt
index of 7091 and an intrinsic viscosity of 2041 at a rate
of 1,450 g/hrO
~he polymer composition was extracted with kerosene
in the same way as in Example lo An amorphous copolymer of
` ethylene and propylene with a propylene content of 65 mole%
was obtainedO ~he proportion of the amorphous copolymer
was 80 89% by weight based on the polymer compositionO
~he polymer composition had a gloss of 4306% and
a deg.ree of whitening of C0
.~; .
