Note: Descriptions are shown in the official language in which they were submitted.
201 4005
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A process for stabilising polyolefins
The present invention relates to a process for stabilising olefin
polymers having a mean particle diameter of from 1 to 5 mm that have been
polymerised on carrier catalysts.
JP-A-84/150 719 describes a process for stabilising polypropylene powder
in which the polypropylene powder, the stabilisers and a carrier are
homogenised in a mixer with the application of heat.
EP-A-281 189 describes a process for producing a hydrolysis-resistant
stabiliser mixture consisting of a phosphate and a phenolic antioxidant,
and the use of that stabiliser mixture for stabilising polypropylene
powder. Pulverulent polyolefin has to be granulated in an extruder before
being shaped. During the granulation, stabilisers and other processing
auxiliaries are added to the polymer.
Unstabilised granular-type polyolefins that have been produced by
polymerising olefins on solid carrier catalysts have been commercially
available for some time. Since these polyolefins are obtained in granular
form when manufactured, they do not need to be extruded in a subsequent
processing step, unless incorporation of the stabilisers and the process-
ing auxiliaries necessitates melting in order to ensure an adequate
distribution of the additive in the polymer.
In many cases the addition of stabilisers during the olefin polymerisa-
tion causes interference with the polymerisation and discolouration of
the polymers.
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The present invention relates to a process for
stabilising olefin polymers having a mean particle diameter of
from 1 to 5 mm that have been polymerised on carrier
catalysts, which comprises treating the polyolefins with a
stabiliser mixture prepared by heating to from 120 to 260°C a
mixture containing components a), b) and c) or components b)
and c) with component a) being at least one carrier, component
b) being at least one stabiliser that melts at from 20 to
120°C, and component c) being at least one stabiliser that
melts at from 120 to 260°C, and then cooling said mixture
until solidified, components b) and c) being different.
Component b) can where appropriate assume the function of
component a) as a carrier.
The ratio by weight of a:c is preferably from 0.1:1
to 4:1, especially from 0.5:1 to 2:1, and the ratio by weight
of b:c is, for example, from 4:1 to 0.1:1 or from 2:1 to
0.1:1, preferably from 1:1 to 0.1:1.
A process in which the stabiliser mixture used
contains components a), b) and c) is preferred.
The carrier is preferably a wax, paraffin oil or a
glyceryl monocarboxylic acid ester. The following may be
mentioned as examples of suitable carriers= polyethylene,
polypropylene (for example atactic), olefinic copolymers (for
example copolymers of propylene, such as propylene/ethylene
copolymer or propylene/butene-1 copolymer), ethylene/vinyl
acetate copolymers, ethylene/(unsaturated carboxylic acid
21489-7987
201 4flfl5
- 2a -
ester) copolymers (for example ethylene/methyl methacrylate
copolymer), ethylene/(unsaturated carboxylic acid metal salt)
copolymers (for example ethylene/magnesium acrylate copolymer
or ethylene/ainc acrylate copolymer), polyethylene or
polypropylene each modified with unsaturated carboxylic acids,
such as, for example, maleic acid anhydride, petroleum,
paraffin oil, polyalkylene glycol, such as, for example,
polyethylene glycol, polypropylene glycol etc., or glyceryl
monocarboxylic acid ester, preferably glyceryl monostearate.
21489-7987
~f;
F
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Depending on the nature of the carrier, it melts, for example, at from
0 to 120°C, from 10 to 120°C or from 20 to 100°C. It is
preferable to use
a carrier that melts either at from 0 to 79°C (for example paraffin
oil)
or at from 80 to 105°C (for example wax).
Component b) is preferably a sterically hindered phenolic antioxidant, a
phosphorus-containing stabiliser, a sterically hindered amine, a benzo-
triazole, a benzophenone, a thiodicarboxylic acid diester and/or a
dialkyl disulfide.
The following stabilisers are examples of component b):
Sterically hindered phenolic antioxidants:
A) 2,2-Bis(3',5'-di-tert-butyl-4'-hydroxyphenylpropionyloxyethoxyphenyl)-
propane
(H3C)3C~
H3
HO-~\~ ~~~-CHZCHZ-~-0-CHZCHZ-0-~~~ ~j.
_. .-. ~H
(H3C)sC/~
2
melting point: 100-102°C
B) Tetrakis(3,5-di-tert-butyl-4-hydroxyphenylpropionyloxymethyl)methane
(H3C)3C~
.-.
HO-~~ j~-CHZCHZ-~-0-CHz C
-.
(H3C)3C~.
4
melting point: 110-120°C
C) n-Octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate
(H3C)3C~
HO-~\~ ~%~-CHZCHz-~-0-C1BH3~-n
(H3C)aC~.-.
melting point: 50-55°C
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D) Triethyleneglycol-bis(3-(3'-tert-butyl-4'-hydroxy-5'-methylphenyl)-
propionate)
(H3C)3C\ /C(CH3)3
HO-~~~ ~j~-CHZCHz-~-0-(CHZCHz-O~~-CHzCHz-~~~ ~j~-OH
-. ._.
HaC/~ \CH3
melting point: 67-79°C
E) 1,5-Bis(3',5'-di-tert-butyl-4'-hydroxyphenylpropionyloxy~-3'-thia-
pentane
(HaC)aC\ /C(CH3)a
HO-~~~ ~j~-CHzCHz-~-O-CHzCHz-S-CHZCHz-0-~-CHzCHz-~~~ ~j~-OH
(HaC)3C/.-. ~=~\C(CH3)a
melting point: 63-68°C
Phosphorus-containing stabilisers:
F) Tetrakis(2,4-di-tert-butylphenylj-diphenylene diphosphonite
j (CH3)a (H3C)aC\
(H3C)aC-~~. .~ P-~~.-.\ ~/~-~\ _P 0-~/. ~~ -C(CHa)s
\ /~ \ /~ \ /~ \ /~
.-. ._. ._. .-.
z z
melting point: 75-95°C
G) Distearylpentaerythritol diphosphite
/0-CHz\ /CHz 0\ _
Ha~Cla-0-P\ /C\ /P 0-C18H3~
O-CH z CH z-0
melting point: 40-60°C
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Stericallv hindered amines:
H) Bis(2,2,6,6-tetramethyl-4-piperidinyl]sebacate
H3C~ /CH3 H3C~ /CH3
HN\~ ~ j~-0-~-(CHz ) s-~-0-.\. ~~H
H3C~~~CH3 H3C~~~~CH3
melting point: 82-86°C
I) Bis[1,2,2,6,6-pentamethyl-4-piperidinyl]sebacate
H3C~ /CH3 H3C~ /CH3
H3C-N\. '~~-0-~-(CHz)s-~-0-.\.-.~-CH3
H3C~~~CH3 H3C~~~CH3
melting point: 20°C
J) Bis(2,2,6,6-tetramethyl-4-piperidinyl]succinate
H3C~ /CH3 H3C~ /CH3
HN\~ ~ j~-0-~-( CHz ) z-~-0-.\. ~~H
H3C~~~CH3 H3C~~/~CH3
melting point: 120°C
K) Condensate of 1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol
and succinic acid
HaC~ j Ha
~/ H
HOCHZCHz-N\~ ~j~~ + HO-~-(CHz)z-~-OH
~ OH
H3C~~~CH3
melting point: 55-70°C
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Benzotriazoles:
L) 2-(2'-Hydroxy-5'-tert-octyl)benzotriazolel
~~\
I I ~-
.\./.\N .\.__ /
~\CeHl -t
melting point: 103-104°C
M) 2-(2'-Hydroxy-3',5'-di-tert-pentyl)benzotriazole2
./~\ QH j SH11-t
I I ~- /~ ~\
~\CsHii-t
melting point: 79-87°C
Benzophenone:
N) 2-Hydroxy-4-octyloxybenzophenone
~H
%.\ _ _ %.\
I II ~ I II
Hm C80/~~,/.
melting point: 47°C
Thiodicarboxvlic acid diesters:
0) Dilauryl thiodipropionate
Hz5C1z00CCHzCHz-S-CHzCHZC00C1zHzs
melting point: 40-45°C
1 tert-octyl = 1,1,3,3-tetramethyl-1-butyl
tert-pentyl = 1,1-dimethyl-1-propyl
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P) Dimyristyl thiodipropionate
Hz9C1400CCHZCHz-S-CHZCHZCOOC14Hz9
melting point: 44-48°C
Q) Distearyl thiodipropionate
H37C1800CCHzCHz-S-CHZCHZCOOC18H37
melting point: 57-67°C
Dialkyl disulfides:
R) Distearyl disulfide
H37C18-$$-C18H37
melting point: ~66°C
Component b) is especially preferably sterically hindered phenolic
antioxidant.
Component c) is preferably a sterically hindered phenolic antioxidant, a
metal deactivator, a sterically hindered amine, a benzotriazole, a
phosphorus-containing stabiliser, a nickel-containing UV-absorber and/or
a metal salt of a C16-Czz-fatty acid.
The following stabilisers are examples of component c):
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_$_
Sterically hindered phenolic antioxidant:
a) 1,3,5-Trimethyl-2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-
benzene
H3C ~ CH3 /C(CHa)s
\ /.\ / -
I II in which R = -CHz-~~~ ~j~-OH
R/'~ /'~ .-.\
1~ C(CH3)3
CH3
melting point: 242-245°C .
f3) 1,3,5-Tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanurate
~\ /R /C(CH3)a
in which R = -CHz-~~1 ~j~-OH
._.\
C(CH3)3
melting point: 218-223°C
y) 1,3,5-Tris(2',6'-dimethyl-4'-tert-butyl-5'-hydroxybenzyl)isocyanurate
/R H3C\ _
in which R = -CHz-~~~ ~j~-C(CH3)3
/'~~~ .-
0 0 H3C/ ~\OH
melting point: 145-155°C
d) 1,2-Bis[3',3'-bis(4"-hydroxy-5"-tert-butylphenyl)butanoyloxy)ethane
QH
/~\ /C(CH3)a
I II
.\ /.
H3C-~-CHz-~-~CHz
~~\
I II
~\ /~\C(CHa)a
~H
z
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melting point: 170°C
e) Bis(3-tert-butyl-4-hydroxy-6-methylphenyl)sulfide
(H3C)3C\ /C(CH3)3
HO-~\. .~.-S-,\._.~~-OH
._ ._.
H3C H3C/
melting point: 161°C
2-(2'-Hydroxy-3'-tert-butyl-5'-methylbenzyl)-4-methyl-6-tert-butyl-
phenyl acrylate
QH CHZ ~OCCH=CHz
(HaC)aC\ /~\ / ~ /~\ /C(CHa)a
I II I II
.\ /. .\ /.
CH3 CH3
melting point: 130-132°C
n) 1,1,3-Tris[3'-tert-butyl-4'-hydroxy-6'-methylphenyl]butane
(H3C)3C\ /C(CH3)3
HO-.\._.~~ H ~\. ~~._OH
._. HZ ._.
H3C HCH3 C~3
H3C\ ~~\
I II
~\ /~\C(CHa)s
~H
melting point: 182.5-190°C
B) 2,4-Di-tert-butylphenyl-3',5'-di-tert-butyl-4'-hydroxybenzoate
/C(CHs)s j (CHa)s
(HaC)sC_~~._./~ ~~ ~\._~/~ OH
\C(CHs)a
melting point: 190°C
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Metal deactivators:
1) N,N-Bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl]hydrazine
(HaC)aC\ /C(CH3)a
.-.
HO-~~ j~-(CHz)z-~-NHNH-~-(CHz)z-~~~ ~j~-OH
.-. ._
(H3C)3C/ ~\C(CH3)a
melting point: 224-229°C
K) N,N-Bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyloxyethyl]oxalic acid
diamide
(HaC)aC\
H~~~~ ~j~-(CHz)2-~-0-(CHz)z-~-
(H3C)3C~~-.
2
melting point: 173°C
Sterically hindered amines:
Poly(2-(N,N-bis(2',2',6',6'-tetramethyl-4'-piperidinyl)hexamethylene-
diamino-4-morpholino-1,3,5-triazin-6-yl]
(CHz)6 ~ ~N\
H3C\I/~\I% H3 H3C\I/~\I% H3
H3C~~~~\CH3 H3C~~~~\CH3
.\0/.
n
melting point: 110-130°C
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u) Poly[2-(N,N-bis(2',2',6',6'-tetramethyl-4'-piperidinyl)hexamethylene-
diamino-4-tert-octyl-1,3,5-triazin-6-yl]
~T ( C H z ) s ~1 ~N\
H3C\I/~\I/CH3 H3C\I/~\I/CH3 \
HN-C8H1~-t
H3C/~~~\CH3 H3C/~\~~\CH3
n
melting point: 120-150°C
v) 1,5,8,12-Tetrakis[2',4'-bis(1",2",2",6",6"-pentamethyl-4"-piperidinyl-
(butyl)amino)-1',3',5'-triazin-6'-yl]-1,5,8,12-tetraazadodecane
H-~-(CHz)a-~-(CHz)zy-(CHz)a-yH
H3C\ /CH3
r4H9 /.-
~NN' .~-CH
.
~ a
\.
.
_ HaC/
~N .\ \CH3
R - . HaC\ /CH3
-.~-CHa
H \.
4 H3C/
9 \CH3
melting point: 150°C
Bis[1',2',2',6',6'-pentamethyl-4'-piperidinyl]-2-butyl-2-(3",5"-di-
tert-butyl-4"-hydroxybenzyl)malonate
HaC\ j H3
/
(H3C)aC\ ~~ ~\~- -CH3
/~\
HO-~~. ~~ -CHz- -C4H9 H3C CH3
\ -_~/~ H3C\ % Ha
(HaC)aC/~ 00 /. .~-CH3
.\ _
H3C/~\CH3
melting point: 146-150°C
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o) 1,2-Bis[3',3',5',5'-tetramethyl-2'-oxo-1',4'-diazinan-1'-yl]ethane
HaC\ /CHa~% 0~ HaC\ j H3
HN\~ ~-(CHz)z-~~ ~/NH
H3C/~\CH3. .H3C/.\CH3
melting point: 136°C
~r )
HjC\ /CH3
0 - \~~
H3C CH3 \~ ~/~\~ ~\~ ~/NH
\ /_ / \ /~\~~ HjC/~\CH3
~J ~\ _ _
HN\~ /~
~ ~ 0
H3C/~\CH3
melting point: 270°C
Benzotriazoles:
p) 2-(2'-Hydroxy-3,5-di-tert-butylphenyl)benzotriazole
~ H C(CH3)3
\ ~_ /
I I ~-~j~ ~~
\~/.\N \~- /.
~\C(CH3)a
melting point: 150-155°C
Q) 2-(2'-Hydroxy-3'-tert-butyl-5'-methylphenyl)-5'-chlorobenzotriazole
C1\ /~\ QH /C(CH3)a
I j - /~
~~ /~~ ~\ _ /
~ ~\CH3
melting point: 137-140°C
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i) 2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)-5'-chlorobenzotriazole
C1\ /~\ QH /C(CH3)a
I j
.\ /.\,. .\ /
\C(CHs)a
melting point: 154-158°C
Phosphorus-containing stabilisers:
v) Tris[2,4-di-tert-butylphenyl]phosphite
(H3C)3C-~~~ ~j'- P
~ ~\C(CH3)a
3
melting point: 180-185°C
Bis[2,4-di-tert-butylphenyl]pentaerythritol diphosphite
C(CH3)a (HaC)aC
_ / 0-. -0 \ _
(HaC)aC-'/~ ~\ -0P/ \~/~ \P-C-~~. '~ -C(CH3)a
\._./~ \~~/ \~-Q/ \._~/.
melting point: 160-175°C
X) Bis[2,6-di-tert-butyl-4-methylphenyl]pentaerythritol diphosphite
/C(CHa)a (HsC)3C\
~ -' 0- ~ -0
H3C-~j ~ -0-P/ \ /~ \P-~~/._.\ -CH3
\~_- /~ \~~/~\~-0/ \ -~/~
~\C(CH3)a (H3C)3C/~
melting point: 235°C
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V~ )
~Ha
(H3C)3C~ ~'~ ~ ~ ~'~ /C(CH3)3
I II ~ II
.\ /.\0 O/.\ /.
(H3C)3~ \~/ ~(CH3)3
melting point: 200-201°C
cu) Calcium salt of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid
monoethyl ester
(H3C)3C~
CzHs _
HO-'~~_./~ CHZ-~ 0 Ca2+
(H3C)3C/~-
2
melting point: >150°C
A) Nickel salt of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid
monoethyl ester
(H3C)jC~ _
CzHs _
HO-~~~ ~ j~-CH2- 0 Ni2+
(H3C)3C/~-.
2
melting point: >180°C
Nickel-containing UV-absorbers:
B) 2,2'-Thio-bis(4-tert-octylphenolato~-butylamino nickel (II)
t-H17C8-.\._.~ 0
jS Ni-NHC4H9
t-H17C8-.\.-.~ 0
melting point: 258°C
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Metal salts of C,s-C~~-fatty acids:
t) Ca palmitate, melting point: 150-155°C (decomposition)
D) Mg palmitate, melting point: 121°C
E) Zn palmatate, melting point: 125°C
Z) Ca stearate, melting point: 180°C
H) Mg stearate, melting point: 145°C
A) Zn stearate, melting point: 130°C
I) Ca behenate, melting point: 150°C
K) Mg behenate, melting point: 150°C
A) Zn behenate, melting point: 125°C
A phosphorus-containing stabiliser, especially a phosphate, is of
interest as component c).
The invention relates especially preferably to a process in which the
stabiliser system used contains components a), b) and c) and in which
component b) is a sterically hindered phenolic antioxidant and compo-
nent c) is a phosphate.
According to another preference, component b) is n-octadecyl-3-(3',5'-
di-tert-butyl-4'-hydroxyphenyl)propionate and/or tetrakis[3,5-di-tert-
butyl-4-hydroxyphenylpropionyloxymethyl]methane and component c) is
tras[2,4-di-tert-butylphenyl]phosphate.
Also preferred is a process in which component b) is a stabiliser that
melts at from 50 to 120°C and component c) is a stabiliser that melts
at
from 180 to 200°C and the stabiliser mixture as heated to from 180 to
200°C.
Components a), b) and c) are known and are for the most part commercially
available products.
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Olefins that can be polymerised on carrier catalysts are, for example,
ethylene or a-olefins, especially propylene, 1-butene, 4-methylpentene-1
or 5-methylhexene-1, and mixtures of olefins, such as, for example,
ethylene/propylene or propylene in admixture with smaller amounts of
higher a-olefins.
Polyethylene, polypropylene, copolymers of ethylene and copolymers of
propylene, especially polyethylene and polypropylene, each applied to
carrier catalysts, are of interest.
The polymerisation catalysts used, which are frequently referred to as
third generation catalysts, are advantageously solid catalysts of a
particular particle size, such as, for example, those described in
DE-A-29 33 997 and DE-A-26 41 960. They consist, for example, of an
anhydrous magnesium dihalide in active form and a titanium compound.
Magnesium dihalide in active form denotes one in the X-ray spectrum of
which the line of strongest reflection is broadened compared with the
corresponding line in the spectrum of inactive magnesium halide.
Preferably, magnesium dichloride or magnesium dibromide is used as
magnesium dihalide. The titanium compound contains preferably at least
one titanium-halogen bond, the use of titanium tetrachloride being
especially preferred.
The titanium compound can be used in combination with an electron donor,
for example a carboxylic acid ester, such as that described in
EP-A-45 977.
After reaction of the magnesium halide component with the titanium
compound and, where appropriate, with the electron donor, the excess
titanium compound and the excess electron donor are advantageously washed
out with an inert solvent, for example with hexane or heptane.
The catalyst prepared in this manner is activated by reaction with an
aluminium alkyl, which is preferably used in the form of a solution in an
alkane. Examples of suitable aluminium alkyls are A1(CzHs)a or A1(CaH9)3.
There may be added as coactivator an electron donor such as, for example,
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an organic silicon compound that contains at least one Si-0-C bond, such
as that described, for example, in EP-A-45 977. Examples of such silicon
compounds are phenyltriethoxysilane, phenyltrimethoxysilane, diphenyldi-
methoxysilane, methyltriethoxysilane, dimethyldiethoxysilane and ethyl-
trimethoxysilane.
The polymerisation with these catalysts can be carried out according to
known methods in liquid or gaseous phase. The liquid phase may be, for
example, an aliphatic hydrocarbon, or the liquid monomer itself.
Spherical polymerised polyolefins are also described, for example, in
P. Galli, P.C. Barbe and L. Noristi; "High Yield Catalysts in Olefin
Polymerization", Die Angewandte Makromolekulare Chemie 120 (1984),
p. 73-90 (No. 1935).
The diameter of the olefin polymers polymerised on carrier catalysts is
preferably from 2 to 5 mm, especially from 2 to 3 mm.
The melting point of these granular-type polyolefins is, for example,
from 140 to 165°C.
The concentration of the stabiliser mixtures in the polyolefin to be
stabilised is preferably from 0.01 to 5 % by weight, especially from
0.05 to 1 % by weight.
Before incorporation into the polyolefin, it is advantageous to heat the
stabiliser system until a milky solution has formed. This milky solution
is a suspension of component c) in a) and/or b). For stabilisation, the
polyolefin is stirred, for example for from 2 to 10 minutes, in a
suitable device (preferably a mixer) with the stabiliser system, which
has a temperature of, for example, from 60 to 120°C, preferably from
100 to 120°C, especially from 100 to 110°C, and then cooled.
Advantage-
ously, the polyolefin is heated, for example to approximately from 60 to
120°C, before stabilisation.
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The temperature of the polyolefin may be, for example, from 60 to
79°C if
the stabiliser system contains as carrier a substance that melts at
approximately from 0 to 79°C, such as, for example, paraffin oil, or if
the stabilizer system has subsequently been treated with paraffin oil.
The ratio by weight of stabiliser system to paraffin oil is in the latter
case, for example, from 1:1 to 3:1. In the case of subsequent treatment
of the stabiliser system with paraffin oil, the stabiliser system is
advantageously stirred into hot paraffin oil (from 100 to 120°C) and
then
stirred (for example for from 15 to 30 minutes) until a homogeneous
mixture is obtained which can be used for the stabilisation of the
polyolefin.
If a substance that melts at approximately from 80 to 110°C is
used as
carrier, such as, for example, wax, it is advantageous if the temperature
of the polyolefin is, for example, from 80 to 120°C, preferably from
80 to 110°C.
The preparation of the stabiliser system is advantageously carried out by
mixing components a) and/or b) and c). The mixture is heated, for example
to from 120 to 260°C, preferably with stirring. The resulting melt is
stirred, for example, for from 2 to 15 minutes, preferably from
8 to 12 minutes, and then cooled until it solidifies, which occurs, for
example, at a temperature of from 0 to 30°C. The cooling can be
effected,
for example, with cold water or some other inert liquid, or with nitrogen
or some other inert gas. It is also possible to cool the melt, for
example, using a cold metal plate.
The preparation of the stabiliser system can also be effected, for
example, in a kneader, in which case the stabiliser mixture is obtained
in the form of a granulate.
The following Examples further illustrate the invention.
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Example 1: Preparation of the stabiliser mixtures.
Stabiliser mixture I:
20 g of n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate,
50 g of tetrakis[3,5-di-tert-butyl-4-hydroxyphenylpropionyloxymethyl]-
methane and 100 g of tris[2,4-di-tert-butylphenyl]phosphite as well as
200 g of polyethylene wax (melting point according to ASTM D-3104:
102°C,
hardness according to ASTM D-5: 7.0 dmm, density according to
ASTM D-1505: 0.91 g/cc, viscosity according to Brookfield at
140°C:
180 cps) are mixed together and heated to 200°C. The molten material is
stirred at that temperature for 10 minutes. The mixture is subsequently
cooled, also with stirring, and solidifies.
Stabiliser mixture II:
II is prepared analogously to I using glyceryl monostearate instead of
the wax.
Stabiliser mixture III:
III is prepared analogously to I using distearyl thiodipropionate instead
of the polyethylene wax.
Stabiliser mixture IV:
IV is prepared analogously to I using 50 g of polyethylene wax instead of
200 g of polyethylene wax.
Stabiliser mixture V:
V is prepared analogously to IV, the mixing and heating being effected in
an extruder ( BUSS-KO-KNETER) and the additive mixture being prepared in
the form of a granulate.
Examples 2a-2c: Stabilisation of spherical polypropylene pellets.
a) 1000 g of spherical polypropylene ( Moplen SPL 12) are heated to
104°C
for 7 minutes in a~enschel mixer (capacity: 5000 ml). 3.7 g of the
stabiliser mixture given in Table la, which have previously been melted
at 104°C, are added. The mixture is stirred for 2 minutes and then
cooled. The stabilised polypropylene pellets are subjected to oven
29276-155
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ageing at 149°C for 30 h. The test results are given in Table la.
Discolouration of the polypropylene pellets indicates inadequate stabili-
sation.
Table la:
Stabilizer 30 h oven ageing at 149C
mixture
discolouration
I no discolouration
II no discolouration
III no discolouration
b) 1000 g of spherical polypropylene ( Moplen SPL 12) are heated to
65°C
for 3 minutes in ~Henschel mixer (capacity: 5000 ml). 3.7 g of the
stabiliser mixture given in Table lb, which have previously been heated
to 104°C, are added. Further processing and testing are carried out as
in
a). The test results are given in Table lb.
Table lb:
Stabilizer 30 h oven ageing at 149C
mixture
discolouration
III no discolouration
c) 1000 g of sphe ~ al polypropylene ( Moplen SPL 12) are heated to
65°C
for 3 minutes in a Henschel mixer (capacity: 5000 ml).
2.2 g of the stabiliser mixture given in Table lc are added to 1 g of hot
paraffin oil (110°C) and the resulting mixture is stirred at that
temperature for 20 minutes. The mixture is then added to the poly-
29276-155
2014005
- 21 -
propylene (65°C) and the mixture is stirred for 2 minutes and then
cooled. The polypropylene pellets are tested as in a). The test results
are given in Table lc.
Table lc:
Stabilizer 30 h oven ageing at 149C
mixture
discolouration
IV no discolouration
V no discolouration
