Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2~ ~3~9~
HOECHST AKTIENGESELLSCEIAFT HOE 92/F 241 Dr.I:~A/-
Description
Process for preparing a polypropylene wax
The invention relates to a process for preparing
polypropylene waxes of high crystallinity by
homopolymerization of propylene or copolymerization of
propylen~ with a small fraction of other olefins, to the
catalyst used for this purpo~e and to the waxe~ prepared
by this process.
It is known that the polymerization of propylene in the
presence of a catalyst, obtain~d by reacting a titanium
compound with a magnesium compound, at a relatively high
temperature leads to waxy polym~rs having a comparatively
high melt viscosity (cf. DE 2,329,641). The crystallinity
of these waxes i~ in the lower to medium range and can be
influenced within certain limits by the nature o~ the
aluminum-organic compound u~ed for activation, but at
most only moderake degrees o~ crystallinity are obtained.
Moreover, highly crystalline poly-l-alkene waxesd in
particular polypropylene waxes, are accessible by using
a specific ca~alyst sy~tem composed of the reaction
product of titanium tetrahalide, ma~nesium alcohvlate and
an ether, alcohol, amine or a carboxylic acid or a
carboxylic acid derivative ~cf. DE 3,148,229)~ Addition-
ally, a further, stereoregulating component selected from
the group comprising carboxylic acid e~ters, phosphoric
acid amides, ethers or thioethers is added during the
polymerization. The polymerization i8 carried out in
solution in a temperature range from 100 to 110C. At a
higher polymerization temperaturel the cry~tallinity of
the products decreases. A di~advanta~e o~ this process i8
that the required low polymerization temperature~ are a~
a rule below the cloud point of the waxes formed, ~o that
the Iatter precipitate and hence cause the formation of
undesixed deposits in the reactor.
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Finally, a process for the preparation o~ "exclusively
isotactic~ polypropylene waxes by bulk polymerization
with the aid of a titanium halide and an aluminum-organic
compound at a temperature in the range from 180 to 350C
and a pressure from 500 to 3000 bar is known ~cf.
DE 3,431,842). The process involves a hîgh energy con-
sumption and rsquires expensive pressure and tempe.ra-
ture-resistant equipment.
In addition, the preparation of highly isotactic homo-
polymeric and copolymeric polypropylene waxes by a gas
phase proce~s is known, in which supported catalysts
containing titanium and magnesium are used in combinat.ion
with aluminum-organic activators and electron donors such
as, for example, alkoxysilane compounds (cf.
DE 4,030,379). The products acce~sib].e by this process
are, however, comparatively high-molecular~ Their further
processing by the melt technology, which is usual for
waxes and presupposes low vi~aosities, is not po~ible
with these, or at least difficult.
It is also known that polypropylene waxes can be prepared
with the aid o~ soluble catalyst systems containing
metallocene compounds ~cf. DE 3,743,321, D~ 3,904,468 and
DE 3,743,320). ~he synthesis and handling of the metallo-
cene components and espeGially of the al~minoxane compon~
ents used as co-catalysts in a large excess is expensive.
It has now been ~ound that polypropylene waxes of high
crystallinity and good processibility can be obtained by
solution polymerization at a temperature above 110C, if
a specific catalyst system in combination with a silicon
compound is used in the polymerization.
The invention therefore relat~s to a proceæs for prepar-
ing a polyolefin wax having an IR isotacticity of ~ 70 ~
and a melt v.iscosity of 50 to 4000 mPa.s, measured at
170C, by homopolymerization of propylene or copolymeriz
ation of propylene with 0.1 to 5 ~ by weight of ethylene
, ' ' ' .
21036~4
- 3 -
or of an ol~fin of the formula R-CH=CH2, in which R is an
alkyl radical having 2 to 38 carbon atoms, in solution at
a temperature of 2 110C at a pressure of 2 to 100 bar in
the presence of a catalyst system composed of a titanium-
containing componen~ ~, a silicon-containing component B
and an aluminum~organic component C, wherein component A
has been prepared by reacting a magnesium compound of the
formula I
Mg~ORl)~X~n
(I),
in which Rl is identical or different Cl-510-al}cyl
radicalsl X is a halogen atom and n is 1 or 2, with a
tetravalent ti-tanium compound of the formula II
Ti~OR2)mX
(II~,
in which R2 iS identical or different Cl-C6-alkyl
radicals, X is a halogen atom and m is a number from 0
to 4,
a silicon compound of the formula III
R3pSi(oR4)4p (III)
in which p is 1, 2 or 3 ~ ~3 is identical or di~ferent
Cl-Cl6-alkyl radicals and R4 is identical or different
cl-c16-alkyl radicals or unsubstitu-ted or
alkyl-substituted C5-C8-cycloalkyl radicals, C6-Cla-aryl
radicals or C7-C1a-aralkyl radicals, is used as compon-
ent ~ and
an aluminum compound of the formula IV
R5qAlCl3 g
in which q is 1, 2 or 3 a~d R5 is identical or di~ferent
C1-C30-al~yl radicals, i8 used as component CO
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The preparation of the cataly~t is carried out in such a
way that initially the catalyst component A i~ prepared
by reacting a magnesium compound, pre~erably a magnesium
alcoholate, with a tetravalen~ titanium compQund, prefer-
ably a titanium tetrahalide, in an in~_rt solvent. Themagnesium alcoholate used is a compound of the formula I
Mg(OR~ 2-~
(I),
in which Rl is identical or different, preferably
straight chain C,-C,0-alkyl radicals, preferably C,~C6-
alkyl radicals, X is a halogen atom and n is 1 or 2.
~y(OCH3) 2 r Mg~oc2Hs) 2 / ~g ( ~C3H,) 2 and Mg( OC4~9 ) 2 may be
mentioned as examples. ~owe~er, magnesium alcoholates of
the formula MgX(OR'), in which X is halogen and R' i~ as
defined above, can also be used.
The magnesium compound is reacted with a tetrclvalent
titanium compound of the formula II
Ti(OR2)~X4m
(II),
in which R2 is identical or dif~erent C,-C6-alkyl
radicals, X is a halogen atom and m is a numbar from 0
to 4, at a temperature from 0 to 200, preferably 20 to
120C. The reaction medium used i~ an inert diluent and
~uspending agent, for example a hydrocarbon. Aliphatic
and cycloaliphatîc hydrocarbons ~uch as, for example~
hexane, heptane or cyclohexane and also aromatia hydro-
carbons such a~ benzene, toluene etc~ are suitable.
Advantageously, the magne~ium component is introduced as
a suspen~ion, and the titanium compound is added with
stirring~ The magnesium compound and ti~anium com~ound
are expediently and preferably used in a molar ratio of
l : 0.2 to 1 : 5/ but molar ratios out~ide this range are
also possible. The reaction times are in general between
1 and 10 howrs.
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-- 5 --
The catalyst component A thus obtained axises as a solid.
It is freed of soluble fractions by xepeated washing with
an inert hydrocarbon~ preferably with the medium used in
its preparation. The washed catalyst can, if de~ired, be
reacted with an electron donor. Suitable! electron donors
are alcohols such as methanol, ethanol and propanol,
ethers such as diethyl ether, di-n butyl ether or di-i-
amyl ether, amines such as triethylamine, aliphatic or
aromatic carboxylic acids and derivatives thereo~, for
example esters, anhydrides, halides or amides su~h a~,
for example, ethyl acetate, ethyl benzoate, benzoic
anhydride and benzamide.
The component B used is a silicon compound of the
formula III
R3pSi(oR4)4p (III~,
in which p is 1, 2 or 3, ~3 iS identical or different
Cl-Cl6-alkyl radicals, for example methyl, ethyl or n- or
i-propyl, and R4 is identical or different Cl~C16-alkyl
radicals or unsubstituted or alkylsubætituted Cs-C8-
cycloalkyl radicals, Cj-Cl8-aryl radicals, for example
phenyl radicals, or C7-Cl8-aralkyl radicals, for example
4-methylphenyl radicals. Methyltrimethoxysilane,
ethyltrimethoxysilane, propyltrimethoxysilane,
dimethyldimethoxy~ilane, dimethyldiethoxysilane,
isobutylmethyldimethoxysilane, trimethylmethox~silane,
cyclopentylmethyldimethoxysilane, cyclohexylmethyldLmeth-
oxysilane, phenyltrimethoxy~ilane and diphenyldimethoxy-
silane may be mentioned as examples of component B.
As the aluminum-vrganic component C, compounds of the
formula IV
RsqAlCl3 q ( ~V)
are used, in which q is 1, 2 or 3 and R5 is identical or
different Cl-C30-alkyl radicals, preferably C2-C12-alkyl
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-- 6 --
radicals. The Cl/Al atomic ratio is accordingly between
2 : 1 and 0 : 1. Preferably, a ratio between 1 : 1 and
0.25 : 1 is set, which can be effected by mixing
aluminum-organic compounds of different chlorine content,
for example triethylaluminum and diethylaluminum
chloride.
Using the catalyst system according to the invention,
propylene or propylene with 0.1 to 5 % by weight of
ethylene or an olefin of the formula R-C~=CH2, in which R
is an alkyl radical having 2 to 38 carbon atoms, ~or
example 1-butene or 1-hexene, are polymexized.
The procedure for carrying out the polymerization is
advantageously such that the catalyæt system is first
prepared by reacting component C with component B by
mixing in the presence of an inert hydrocarbon and then
adding component A to this mixture. The quantities are to
be salected here in ~uch a way that the component C
(relative to al~minum~/component B molar ratio i5 200 : 1
to 1 : 1, preferably 50 : 1 to 10 : 1, and the compon-
ent C (relative to aluminum)/component A (relative to
titanium) molar ratio is 1 : 1 to 30: 1, pref0rably
2 : 1 to 20 ~
The polymerization is carried out continuously or discon-
tinuously in solution at a temperature above 110C,
preferably ~etween 115 and 150C, particularly pre~erably
between 120 and 140C, at a pressure of 2 to 100 bar,
preferably 5 to 20 bar. It is also possible to polymerize
in inert hydrocarbvns which are liquid at the polymeriza-
tion temperature but solid at room temperature.
The molecular mass is regulated in the known m~nner by
addition of hydro~en. After completion of the
polymerization, the solvent is ~eparated off, pre~erably
by distillation, if necessary a~ter prior decompo~ition
of the catalyst with suitable decomposing a~ents, for
example wat r, and subsequent fi~tration.
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-- 7 --
The pol~olefin waxes prepared by the process accoxding to
the invention are viscous-hard, colorless, non-tac~y,
heat-stable, readily grindable products having a degxee
of isotacticity, determined by IR spectroscopy, of more
than 70 % and a melt viscosity of 50 to 4000 mPa.s,
measured at 170C. The waxes are suitable, for example,
as base masses for pigment preparation, for an
abrasion-resistant finish of printing inks, for dulling
paints, as an aid in the processing of plastics, for
example as lubrican~s and release agents, as a
formulation component ia photographic toners and as
agPnts for increasing the melting point~
The examples which follow serve to explain the invention
in more detail.
The melt viscosities were mea~ured in a rotary visco-
meter. The determination of isotacticity was carr:ied Ollt
by IR spectroscopy according to J.P. Luongo, J. Appl.
Pol. Chem. 3 (9), 302 (1960), and the heat of fusion was
determined by DSC spectro~copy.
Example 1
114.4 g (1.0 mol~ of magnesium ethylate were suspended in
1000 cm3 of a diesel oil fr~ction (boiling range 140 to
160C). 284.8 g (1.5 mol) of titanium tetrachloride were
added dropwise to the batch with stirring ~t 85C in the
course of 4 hours. 1~he suspension was then stirred for a
further 30 minutes at 85C. The precipitate wa~ wash0d by
repeated stirring with diesel oil, until the supernata~t
diesel oil above the solid was free of titanium.
The catalyst system used for the polymerization was
prepared by mixing 150 mmol of triethylaluminum, 75 mmol
of diethylalu~inum chloride (catalyst component C) and
7.5 mmol of cyclohexylmethyldimethoxy~ilane (component Bl
in 1.5 dm3 0~ diesel oil fraction and subse~uently stixr-
ing 30 mmol (relative to Ti) of the above c~taly~t
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-- 8 --
component A into this mixture. The molar ratio of the
said componerlts was 5 : 2.5 o 0.25 : 1.
15 dm3 of a diesel oil fraction (boiling range 140 to
160C~ were introduced into a 40 dm3 vessel with impeller
stirrer. After heating of the vessel contents to 130C,
hydrogen gas was fixst added up to an internal pressure
of 0.1 bar, and then propylene up to an internal pressure
of 5 bar~ 0.5 dm3 of the catalyst described above waq
pumped in at 130C. By continuou~ further addition of
3.2 kg of propylene and 0.5 dm3 of hydrogen per hour cmd
intermittent addition of catalyst, the pressure was
maintained at 5 bar~ The polymerization temperature wa.
130C.
A~ter 75 minutes, a total of 1~50 cm3 of the catalyst
suspen6ion, corresponding to ahout 21 m~ atom of Ti, had
been consumed. The reaction was stopped by addition of
15 cm3 of water, the polymer solution was filtered and
khe solvent was distilled off in vacuo. This gave 3.55 kg
of polypropylene wax.
Melt viscosity at 170C 1330 mPa.s; heat of fusion
83 J/g; IR isotacticity 72 %.
Comparison ~xample 1
The catalyst component A wa~ prepared according to
Example 1. The catalyst system u~ed for polymerization
was composed of 90 mmol of triethylaluminum, 60 mmol of
diethylaluminum chloride and 30 mg atom of component A.
A silicon compound was not used.
The polymerization of propylene under the conditions
described in ~xample 1 led to a wax product which had a
lower crystallinity than that obtained accordincJ to
~xample 1.
Melt viscosity at 170C: 13~0 mPa.s; heat of fusion
.
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g
63 J/g; IR isotacticity 63 %.
Comparison Example B
A polymerization catalyst was preparled according toDE-A 3,148,229, Example 1~ For this purpose, 114.4 g
(1.0 mol) of magnesium ethylate were suspended in
1000 cm3 of a diesel oil fraction (boi:Ling range 140 -
160C). 380 q (2.0 mol) of titanium tetrachloride were
added dropwise with stirring at 85C in the course of
4 hours. The batch was then stirred for a further 30 min
utes at 85~C. The precipitate was washed by decanting and
repeated stirring with diesel oil, until the dies~l oil
supernatant above the solid was free of titanium.
31.7 g (O.20 mol) of di-isoamyl ether as an electron
donor were then added to the suspension, and the mixture
was stirred for 1 hour at 100C. The solid was freed of
soluble titanium compound~ by washing with diesel oil.
Using this catalyst, propylene was polymerized according
to Example 1 of DE-A 3,14~,~29, but a polymerizatiDn
temperature of 130C was chosen in place of the indicated
~0 100C~ The resulting polypropylene wax showed the follow-
ing characteristic data:
Melt viscosity at 170C 810 mPa.s; heat of fu~ion 79 J/g;
IR-isotacticity 71 %.
As can be seen, the isotaatiaity value of the wax i8
markedly lower than that of a product prepared ln the
same manner but at 100C (85 %). If the polymerization is
carried out at 100C according to DE 3,148,229, the
isotacticity value is admittedly higher, but the inner
wall of the polymerization vessel shows depo~its of
precipitated product, which impede the removal o~ the
heat of reaction.
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-- 10 --
Example 2
The polymerization was carried out according to
Example l. The cataly~t was prepared by mixing 210 mmol
of triethylaluminum, 105 mmol of diethylaluminum chlor-
ide, 22.5 mmol of cyclohexylmethyldime~thoxysilane and30 mg atom of the catalys~ component ~ fxom Example 1,
corresponding to a molar ratio of 7 : 3.5 : 0O75 : 1.
This gave a polypropylene wax having the following
characteristic data:
Melt viscosity at 170C 1990 mPaOs; heat of fu~ion
106 J/g; IR isotacticity 80 %.
Example 3
114.4 g of mag~esium ethylate were ~uspended in lO00 cm3
of a diesel oil fraction (boiling range 140 to 160C).
380 g (2.0 mol) of titanium tetrachloride were added
drop~ise to the batch with ~tirri.ng at 85C in the course
of 4 hours. The suspension was then stirred for a further
30 minutes at 85C. The precipitate was washed by repeat-
ed stirring with diesel oil, until the diesel oil super-
natant above the solid was free of titanium.
31.7 g of diisoamyl ether (200 mmol) were then added to
the suspension, and the mixture was stirred for 1 hour at
100C. The solid was again freed of soluble titanium
compounds by washing with diesel oil. It still contained
3.5 % of the titanium originally introduced as titanium
tetrachloride.
The polymerization was carried out according to
Example 1. The cataly t system was prepared by mixing
210 mmol of triethylaluminum, 105 mmol of diethylal~minum
chloride/ 2~.5 mmol of cyclohexylmethyldimethoxysilane
and 30 mg atom of catalyst component A, corresponding to
a molar ratio of 7 : 3.5 : 0.7S : 1. This gave a polypro-
pylene wax having the following characteri~tic data:
Melt viscosity at 170C 1200 mPa.~; heat o~ fusion
.
-
.
2~369~
110 J~g; IR isotacticity 84 ~.
Example 4
The catalyst system used for the polymerization wasprepared analogously to Example 1, diphenyldimethoxy-
silane being used in place of cyclohexylmethyldimethoxy-
silane. The polymerization of propylene, carried out a~
described in Example 1, gave a wax having the following
characteristlc data:
Melt viscosity at 170C 1600 mPa.s; heat of fusion
82 J/g; IR isotacticity 73 ~.
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