Note: Descriptions are shown in the official language in which they were submitted.
WO 00169940 CA 02372178 2001-11-15 PCTIEP00/04032
. ~ ' l.e~ ~3 ~ 8s
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Process for the production of thermoplastic moulding compositions using
rubber solutions
This invention relates to a process for the production of ABS thermoplastics
and
high impact polystyrenes (hereinafter referred to as HIPS - high impact
polystyrene), wherein vinyl aromatic/diolefin copolymers in random form
dissolved
in vinyl aromatic compounds and produced by transition metal catalysts in
vinyl
aromatic compounds as the solvent are used as rubbers.
Bulk and solution polymerisation processes for the production of ABS moulding
compositions are known and are described in Houben-Weyl, Methoden der
Organischen i.nemie, volume E20/part 1, pp. 182-217, Georg Thieme Verlag,
Stuttgart. The production of HIPS is also known and described, for example, in
BeckeriBraun, Kunststoff=Handbuch, volume 4, Polystyrol, pp. 109-120, ISBN 3-
l~ 446-18004-4, 1996, Carl Hanser Verlag and Styrene Polymers, Encyclopedia of
Polymer Science & Engineering, volume 16, pp. 1-246, 2"d edition, 1989, John
Wiley & Sons. These processes involve dissolving rubbers in vinyl aromatic
monomers (for example styrene) and ethylenically unsaturated nitrite monomers
(for
example acrylonitrile) and optionally solvents and polymerising the monomers.
During polymerisation, phase s~:,paration occurs between the polymer solution
containing rubber and the polymer solution not containing rubber. The polymer
solution not containing rubber initially forms a discrete, discontinuous
phase. As
monomer conversion proceeds, a phase inversion occurs, i.e. the phase of the
polymer solution not containing rubber becomes larger and the rubber solution
becomes the discontinuous phase, while the polymer solution not containing
rubber
forms the homogeneous phase.
ABS and HIPS moulding compositions are produced, using known bulk, solution or
suspension polymerisation processes, by continuous, semi-continuous or batch
production of the rubber solutions produced by dissolution in the presence of
further
WO 00169940 CA 02372178 2001-11-15 PCT/EPOOI04032
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monomers and optionally solvents and are isolated using known evaporation
methods.
A disadvantage of many process for the production of ABS and HIPS using the
bulk,
solution or suspension process is that soluble rubbers are used in solid form,
which
are dissolved in styrene and/or further monomers and optionally solvents and
are
then added as a rubber solution to the remainder of the polymerisation
process. In
order to be dissolved, the solid rubbers must be chopped into small pieces and
dissolved in a dissolving tank in styrene and/or further monomers and
optionally
solvents. Using rubbers in solid form is disadvantageous because these soluble
rubbers are preferably produced by solution polymerisation, wherein aliphatic
and/or
aromatic solvents, which are inert during polymerisation and are not
themselves
active in the polymerisation reaction, are used as the solvents and wherein
the
solvents must optionally be removed by distillation after polymerisation in
order to
isolate the resultant rubbers in solid form. A further disadvantage is that
rubbers
having elevated cold flow or highly tacky rubbers may be processed and stored
only
with difficulty.
Attempts have already been made to produce vinyl aromatic/diolefin copolymers
in
vinyl aromatic compounds as the solvent and to use these rubber solutions for
the
production of ABS and HIPS moulding compositions.
In US 4311819, anionic initiators, such as for example butyllithium, are used
for
polymerising butadiene in styrene. According to the Examples of the patent, it
was
possible to obtain an SBR rubber suitable for HIPS production, either by
terminating
polymerisation as early as at a butadiene monomer conversion of approx. 25%
with
an initial concentration of butadiene in styrene of approx. 35 wt.%, or by
increasing
the butadiene monomer conversion to approx. 36% by means of an elevated
butadiene content of approx. SS wt.%, such that the majority of the introduced
butadiene must be separated by distillation before subsequent use of the
rubber
solution in styrene for impact modification.
WO 00/69940 CA 02372178 2001-11-15 PCTIEP00/04032
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The disadvantage of anionic initiators is that they result in the fannation of
styrene/butadiene copolymers (SBR) which, in relation to the butadiene units,
permit
only slight control of microstructure. By adding modifiers, it is only
possible to
increase the proportion of 1,2 or 1,4-trans units, which results in an
increase in the
glass transition temperature of the polymer. It is not possible using anionic
initiators
to produce an SBR having an elevated cis content in which the 1,4-cis content,
relative to the butadiene content, is above 40%, preferably above 50%,
particularly
preferably above 60%. This fact is primarily disadvantageous because SBR is
formed in this process in which, in comparison with homopolymeric
polybutadiene
(BR), a rising styrene content results in a further increase in the glass
transition
temperature. However, if the rubber is to be used for impact modification of
for
example HIPS or ABS, an elevated glass transition temperature of the rubber
has a
disadvantageous effect on the low temperature properties of the material, such
that
rubbers having low glass transition temperatures are preferred.
US 3299178 claims a catalyst system based on TiCl,/iodine/Al(iso-Bu)3 for the
polymerisation of butadiene in styrene to form homogeneous polybutadiene.
However, in more recent literature, Harwart et al., Plaste and Kautschuk, 2418
?0 (1977) 540, have described the copolymerisation of butadiene and styrene
using the
same catalyst system and, moreover, the suitability of the catalyst for the
production
of polystyrene. This catalyst system is accordingly unsuitable for the
production of
vinyl aromatic/diolefin copolymers in vinyl aromatic solvents.
US 5096970 and EP 304088 describe a process for the production of
polybutadiene
in styrene using catalysts based on neodymium phosphonates, on organic
aluminium
compounds, such as di(isobutyl)aluminium hydride (DIBAH), and based on a Lewis
acid containing halogen, such as ethylaluminium sesquichloride, in which
butadiene
is reacted in styrene without further addition of inert solvents to yield a
1,4-cis-
polybutadiene. A disadvantage of this catalyst is that the resultant rubbers
have a
very low content of 1,2 units of below 1%. This is disadvantageous because a
higher
' WO 00169940 CA 02372178 2001-11-15 PCT/EP00104032
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1,2 content in rubbers has a favourable effect on the grafting behaviour
between the
rubber and the polymer matrix, for example homo- or copolymers of vinyl
aromatic
compounds.
Kobayashi et al, J. Polym. Sci., Part A, Polym. Chem., 33 (1995) 2175 and 36
(1998)
241 have described a catalyst system consisting of halogenated rare earth
acetates,
such as for example Nd(OCOCCI3), or Gd(OCOCF3)3, with tri(isobutyl)aluminium
and diethylaluminium chloride, which allows the copolymerisation of butadiene
and
styrene in the inert solvent hexane. Apart from the presence of inert
solvents, the
disadvantage of these catalysts is that, at a styrene incorporation of as
little as
approx. 5 mol%, catalyst activity falls to below 10 g of polymer/mmol of
catalyst/h
and that the 1,4-cis contenC of the polymer falls distinctly as the styrene
content
rises.
The rubber solutions in styrene described in the stated patent publications
have been
used for the production of HIPS by combining the rubber solutions in styrene
with
free-radical initiators after removal of the unreacted butadiene monomer.
On the other hand, the rubber is used in a matrix of acrylonitrile/styrene
copolymer
(SAN) in order to produce ABS. In contrast with the production of HIPS, the
SAN
matrix in ABS is incompatible with polystyrene. If homopolymers of the
solvent,
such as polystyrene, are formed as well as the rubber, when the diolefins are
polymerised in vinyl aromatic solvents, the incompatibility of the SAN matrix
with
the homopolymerised vinyl aromatics during the production of ABS results in
distinct impairment of material properties.
WO 97138031 and WO 98/07766 describe that styrene/butadiene copolymers or
polybutadiene homopolymers are produced anionically in solution in the
presence of
inert solvents and are used for the production of impact-modified,
thermoplastic
polystyrene moulding compositions and polystyrene/acrylanitrile moulding
compositions. One disadvantage is that inert solvents are added during
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polymerisation of the butadiene, such that the vapours arising after
degassing, which
contain unreacted monomers and solvents, must be separated and dried in an
elaborate manner so that they may be reused in an anionic polymerisation
reaction.
The object of the invention is to provide a process for the production of ABS
and
HIPS moulding compositions by polymerisation in a solution containing rubber,
which process, when suitable catalysts are used, does not exhibit the above-
stated
disadvantages and moreover makes it possible to vary the proportion of styrene
units
in the dissolved rubber.
The process should furthermore make it possible for the rubber solution used
to be
used directly for the production of ABS and HIPS moulding compositions, i.e.
without isolation and redissolution of the rubber in vinyl aromatic compounds.
Said object is achieved by the solution containing rubber being produced by
polymerising diolefins in a solution of vinyl aromatic monomers in the
presence of a
catalyst containing
(A) at least one rare earth metal compound,
(B) optionally at least one cyclopentadiene and
(C) at least one organoaluminium compound.
It has surprisingly been found that the process according to the invention may
be
performed without addition of inert solvents.
The rubber solutions to be used are obtained by polymerising conjugated
diolefins in
vinyl aromatic solvents. In this manner, copolymers are formed in which the
polymer composition may be varied relative to the content of vinyl aromatics
and
diolefins and the selectivity of the polymerised diolefins, such as for
example the
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content of double bonds in cis position and of 1,2 units having lateral vinyl
groups,
wherein the glass transition temperature of the polymers is below -
60°C, preferably
below -70°C. r
The rubber solutions to be used are obtained by polymerising the diolefins in
the
presence of catalysts based on rare earth metal compounds and in the presence
of
vinyl aromatic monomers as solvents at temperatures of -30 to 100°C,
preferably at
temperatures of -20 to 90°C, particularly preferably at temperatures of
20 to 8q°C
using known continuous, semi-continuous or batch processing methods.
Conjugated diolefins which may be used are, for example 1,3-butadiene, 1,3-
isoprene, 2,3-dimethylbutadiene, 2,4-hexadiene, 1,3-pentadiene and/or 2-methyl-
1,3-
pentadiene or mixtures of the stated monomers, with 1,3-butadiene being
preferred.
It is, of course, also possible additionally to use, as well as the conjugated
diolefins,
further unsaturated compounds, such as ethylene, propene, 1-butene, 1-pentene,
1-hexene, 1-octene and/or cyclopentene, preferably ethylene, propene, 1-
butene,
1-hexene and/or 1-octene, which may be copolymerised with the stated
diolefins.
The molar ratio of the catalyst components (A):(B):(C) may be within the range
from 1:0.01-1.99:0.1-1000. Component (A) of the catalyst may be used in
quantities
of 1 umol to 10 mmol, relative to 100 g of the conjugated diolefins used, and
the
aromatic vinyl compound in quantities of 50 g to 2000 g, relative to 100 g of
the
conjugated diolefins used.
The molar ratio of components (A):(B):(C) in the catalyst used is preferably
in the
range from 1:0.1-1.9:3-500, particularly preferably 1:0.2-1.8:5-100.
Rare earth metal compounds (component (A)) which may in particular be
considered
are those selected from among
WO OOI69940 CA 02372178 2001-11-15 PCT/EP00104032
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- a rare earth metal alkoxide,
- a rare earth metal phosphonate, phosphinate and/or phosphate,
- a rare earth metal carboxylate,
- a rare earth metal complex compound with diketones and/or
- an addition compound of rare earth metal halides with an oxygen or nitrogen
donor compound.
The above-stated rare earth metal compounds are described in more detail, for
example, in EP 11 184.
The rare earth metal compounds are in particular based on the elements having
the
atomic numbers 21, 39 and 57 to 71. Preferably used rare earth metals are
lanthanum, praseodymium or neodymium or a mixture of rare earth metal elements
which contains at least 10 wt.% of at least one of the elements lanthanum,
1 ~ praseodymium or neodymium. Very particularly preferably used rare earth
metals
are lanthanum or neodymium, which may in turn be blended with other rare earth
metals. The proportion of lanthanum and/or neodymium in such a mixture is
particularly preferably at least 30 wt.%.
~0 Rare earth metal alkoxides, phosphonates, phosphinates, phosphates and
carboxylates or rare earth metal complex compounds with diketones which may in
particular be considered are those in which the organic group present in the
compounds in particular contains linear or branched alkyl residues having 1 to
20
carbon atoms, preferably I to 15 carbon atoms, such as methyl, ethyl, n-
propyl,
n-butyl, n-pentyl, isopropyl, isobutyl, tert.-butyl, 2-ethylhexyl, neopentyl,
neooctyl,
neodecyl or neododecyl.
Rare earth alkoxides which may, for example, be mentioned are:
.0 neodymium(III) n-propanolate, neodymium(III) n-butanolate, neodymium(III)
n-decanolate, neodymium(III) isopropanolate, neodymium(III) 2-ethylhexanolate,
WO 00169940 CA 02372178 2001-11-15 PCT/EP00/04032
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praseodymium(III) n-propanolate, praseodymium(III) n-butanolate, praseodym-
ium(III) n-decanolate, praseodymium(III) isopropanolate, praseodymium(III)
2-ethylhexanolate, lant~num(III) n-propanolate, lanthanum(III) n-butanolate,
lanthanum(III) n-decanolate, lanthanum(III) isopropanolate, lanthanum(III) 2-
ethyl-
hexanolate, preferably neodymium(III) n-butanolate, neodymium(III) n-
decanolate,
neodymium(III) 2-ethylhexanolate.
Rare earth phosphonates, phosphinates and phosphates which may, for example be
mentioned are:
neodymium(III) dibutylphosphonate, neodymium(III) dipentylphosphonate,
neodymium(III) dihexylphosphonate, neodymium(III) diheptylphosphonate,
neodymium(III) dioctylphosphonate, neodymium(III) dinonylphosphonate, neodym-
ium(III) didodecylphosphonate, neodymium(III) dibutylphosphinate,
neodymium(III) dipentylphosphinate, neodymium(III) dihexylphosphinate,
neodymium(III) diheptylphosphinate, neodymium(III) dioctylphosphinate,
neodymium(III) dinonylphosphinate, neodymium(III) didodecylphosphinate,
preferably neodymium(III) dioctylphosphonate and neodymium(III) dioctylphos-
phinate.
Suitable rare earth metal carboxylates are:
lanthanum(III) propionate, lanthanum(III) diethylacetate, lanthanum(III) 2-
ethyl-
hexanoate, lanthanum(III) stearate, lanthanum(III) benzoate, lanthanum(III)
cyclohexanecarboxylate, lanthanum(III) oleate, lanthanum(III) versatate,
lanthanum(III) naphthenate, praseodymium(III) propionate, praseodymium(III)
diethylacetate, praseodymium(III) 2-ethylhexanoate, praseodymium(III)
stearate,
praseodymium(III) benzoate, praseodymium(III) cyclohexanecarboxylate, praseo-
dymium(III) oleate, praseodymium(III) versatate, praseodymium(III)
naphthenate,
neodymium(III) propionate, neodymium(III) diethylacetate, neodymium(III) 2-
ethyl-
hexanoate, neodymium(III) stearate, neodymium(III) benzoate, neodymium(III)
' . WO OOI69940 CA 02372178 2001-11-15 PCTIEP00104032
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cyclohexanecarboxylate, neodymium(III) oleate, neodymium(III) versatate,
neodym-
ium(III) naphthenate, preferably neodymium(III) 2-ethylhexanoate,
neodymium(III)
versatate, neodymium(IH) naphthenate. Neodymium versatate is particularly
preferred.
Rare earth metal complex compounds with diketones which may be mentioned are:
lanthanum(III) acetylacetonate, praseodymium(III) acetylacetonate,
neodymium(III)
acetylacetonate, preferably neodymium(III) acetylacetonate.
Addition compounds of rare earth metal halides with an oxygen or nitrogen
donor
compound which may be mentioned are:
lanthanum(III) chloride with tributyl phosphate, lanthanum(III) chloride with
tetra-
hydrofuran, lanthanum(III) chloride with isopropanol, lanthanum(III) chloride
with
pyridine, lanthanum(III) chloride with 2-ethylhexanol, lanthanum(III) chloride
with
ethanol, praseodymium(III) chloride with tributyl phosphate, praseodymium(III)
chloride with tetrahydrofuran, praseodymium(III) chloride with isopropanol,
praseo-
dymium(III) chloride with pyridine, praseodymium(III) chloride with 2-ethyl-
hexanol, praseodymium(III) chloride with ethanol, neodymium(III) chloride with
tributyl phosphate, neodymium(III) chloride with tetrahydrofuran,
neodymium(III)
chloride with isopropanol, neodymium(III) chloride with pyridine,
neodymium(III)
chloride with 2-ethylhexanol, neodymium(III) chloride with ethanol,
lanthanum(III)
bromide with tributyl phosphate, lanthanum(III) bromide with tetrahydrofuran,
lanthanum(III) bromide with isopropanol, lanthanum(III) bromide with pyridine,
lanthanum(III) bromide with 2-ethylhexanol, lanthanum(III) bromide with
ethanol,
praseodymium(III) bromide with tributyl phosphate, praseodymium(III) bromide
with tetrahydrofuran, praseodymium(III) bromide with isopropanol,
praseodymium(III) bromide with pyridine, praseodymium(III) bromide with 2-
ethylhexanol, praseodymium(III) bromide with ethanol, neodyrnium(III) bromide
with tributyl phosphate, neodymium(III) bromide with tetrahydrofuran,
WO 00/69940 PCTIEP00/04032
CA 02372178 2001-11-15
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neodymium(III) bromide with isopropanol, neodymium(III) bromide with pyridine,
neodymium(III) bromide with 2-ethylhexanol, neodymium(III) bromide with
ethanol, preferably lanthanum(III) chloride with tributyl phosphate,
lanthanum(III)
chloride with pyridine, lanthanum(III) chloride with 2-ethylhexanol,
S praseodymium(III) chloride with tributyl phosphate, praseodymium(III)
chloride
with 2-ethylhexanol, neodymium(III) chloride with tributyl phosphate,
neodymium(III) chloride with tetrahydrofuran, neodymium(III) chloride with 2-
ethylhexanol, neodymium(III) chloride with pyridine, neodymium(II)7 chloride
with
2-ethylhexanol, neodymium(III) chloride with ethanol.
Very particularly preferably used rare earth metal compounds are neodymium
v ersatate, neodymium octanoate and/or neodymium naphthenate.
The above-stated rare earth metal compounds may be used both individually and
mixed together.
The cyclopentadienes (component (B)) used are compounds of the formulae (I),
(II)
or (III)
,
H R, H R' R Rs H R9 R,
Rs RZ R2
R6 ~ ( \ R / ~ ~ \ RZ
R3 _
3 5
R R R Ra R6 R5 R4 Rs
(1) (II) (III)
in which R' to R9 are identical or different or are optionally joined together
or are
fused on the cyclopentadiene of the formula (I), (II) or (III) and may denote
hydrogen, a C,-C3o alkyl group, a C6-C,o aryl group, a C; C4o alkylaryl group,
a C3-
C3o silyl group, wherein the alkyl groups may be either saturated or mono- or
polyunsaturated and may contain heteroatoms such as oxygen, nitrogen or
halides.
The residues may in particular denote hydrogen, methyl, ethyl, n-propyl,
isopropyl,
WO OOI69940 CA 02372178 2001-11-15 PCT/EP00/04032
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n-butyl, isobutyl, tert.-butyl, phenyl, methylphenyl, cyclohexyl, benzyl,
trimethylsilyl or trifluoromethyl.
Examples of cyclopentadienes are unsubstituted cyclopentadiene,
methylcyclopenta-
diene, ethylcyclopentadiene, n-butylcyclopentadiene, tert.-
butylcyclopentadiene,
vinylcyclopentadiene, benzylcyclopentadiene, phenylcyclopentadiene,
trimethylsilylcyclopentadiene, 2-methoxyethylcyclopentadiene, 1,2-
dimethylcyclopentadiene, 1,3-dimethylcyclopentadiene,
trimethylcyclopentadiene,
tetramethylcyclopentadiene, tetraphenylcyclopentadiene, tetrabenzyl-
cyclopentadiene, pentamethylcycylopentadiene, pentabenzylcyclopentadiene,
ethyltetramethylcyclopentadiene, trifluoromethyltetramethylcyclopentadiene,
indene, 2-methylindenyl, trimethylindene, hexamethylindene, heptamethylindene,
2-
methyl-4-phenylindenyl, fluorene or methylfluorene.
The cyclopentadienes may also be used individually or mixed together.
Organoaluminium compounds (component (C)) which may in particular be
considered are alumoxanes and/or aluminiumorganyl compounds.
The alumoxanes used are aluminium/oxygen compounds which, as is known to the
person skilled in the art, are obtained by bringing organoalumium compounds
into
contact with condensing components, such as for example water, and which
constitute acyclic or cyclic compounds of the formula (-Al(R)O-)~, wherein R
may
be identical or different and denotes a linear or branched alkyl group having
1 to 10
carbon atoms, which may additionally contain heteroatoms, such as oxygen or
halogens and n is determined by the degree of condensation. R in particular
denotes
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert.-butyl, n-octyl or
isooctyl,
particularly preferably methyl, ethyl or isobutyl. Examples of alumoxanes
which
may be mentioned are: methylalumoxane, ethylalumoxane and isobutylalumoxane,
preferably methylalumoxane and isobutylalumoxane.
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The aluminiumorganyl compounds used are compounds of the formula
A1R'°3~Xd,
wherein
r
R'° may be identical or different and may denote a C,-C,° alkyl
group, a C6 to C,°
5 aryl group, a C,-C4° alkylaryl group, wherein the alkyl groups may be
either
saturated or mono- or polyunsaturated and may contain heteroatoms, such as
oxygen or nitrogen,
X denotes a hydrogen or a halogen and
d means a number from 0 to 2.
Organoaluminium compounds of the formula A1R'°3-0Xd which may in
particular be
used are: trimethylaluminium, triethylaluminium, tri-n-propylaluminium, triiso-
15 propylaluminium, tri-n-butylaluminium, triisobutylaluminium,
tripentylaluminium,
trihexylaluminium, tricyclohexylaluminium, trioctylaluminium, diethylaluminium
hydride, di-n-butylaluminium hydride, diisobutylaluminium hydride, diethyl
aluminium butanolate, diethylaluminiumethylidene(dimethyl)amine and diethyl
aluminiummethylidene (methyl) ether, preferably trimethylaluminium, triethyl
20 aluminium, triisobutylaluminium and diisobutylaluminium hydride.
The organoaluminium compounds may again be used individually or mixed
together.
25 A further component (D) may also be added to the well-tried catalyst
components
(A) to (C). This component (D) may be a conjugated diene, which may for
example
be the same diene which is subsequently to be polymerised with the catalyst.
Butadiene and/or isoprene are preferably used.
30 If component (D) is added to the catalyst, the quantity of (D) is
preferably 1 to
1000 mol relative to 1 mol of component (A), particularly preferably 1 to 100
mol.
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Very particularly preferably, 1-SO mol of (D) are used relative to 1 mol of
component (A).
When producing the rubber solutions, the catalysts are used in quantities of 1
pmol
5 to 10 mmol, preferably of 10 pmol to 5 mmol, of the rare earth metal
compound
relative to 100 g of the monomers.
It is, of course, also possible to use the catalysts in any desired mixture
with each
other.
The rubber solution is produced in the presence of vinyl aromatic monomers, in
particular in the presence of styrene, a-methylstyrene, a-methylstyrene dimer,
p-methylstyrene, divinylbenzene and/or other ring-substituted alkylstyrenes,
preferably having 2 to 6 C atoms in the alkyl residue.
The rubber solution is very particularly preferably produced in the presence
of
styrene, a-methylstyrene, a-methylstyrene dimer and/or p-methylstyrene as
solvent.
The solvents may be used individually or as a mixture.
The quantity of vinyl aromatic monomers used as solvent is conventionally 10
parts
by weight to 2000 parts by weight, preferably 30 to 1000 parts by weight, very
particularly preferably 50 to S00 parts by weight, relative to 100 parts by
weight of
monomers used.
The rubber solutions are preferably produced at temperatures of -20 to
90°C,
particularly preferably at temperatures of 20 to 80°C. The process
according to the
invention may be performed without pressure or at elevated pressure (0.1 to 12
bar).
Production may be implemented continuously or discontinuously, preferably with
continuous operation.
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It is also possible to remove a proportion of the solvent used and/or of the
unreacted
monomers after polymerisation, preferably by means of distillation, optionally
under
reduced pressure, in orde~to obtain the desired polymer concentration.
5 The rubber-modified, thenmoplastic moulding compositions according to the
invention are produced by free-radical polymerisation of a vinyl aromatic
monomer
and an ethylenically unsaturated nitrile monomer, or of a vinyl aromatic
monomer in
the presence of one of the above-described rubber solutions with the addition
of an
ethylenically unsaturated nitrile monomer and optionally with the addition of
further
10 vinyl aromatic monomer and optionally in the presence of solvents using
known
bulk, solution or suspension polymerisation processes operated in a
continuous,
semi-continuous or batch manner.
Styrenelbutadiene copolymer solutions in styrene, as may be produced as
described
15 above, are preferably used for the rubber-modified thermoplastic moulding
compos-
itions according to the invention and in the process according to the
invention for the
production thereof.
Rubber solutions are preferably used in which the dissolved styrenelbutadiene
20 copolymers have a styrene unit content of 5 to 40 mol%, particularly
preferably of
10 to 30 mol% and, relative to the content of butadiene, have a content of 1,2
units,
i.e. of lateral vinyl groups, of 2 to 20 mol%, particularly preferably of 4 to
15 mol%,
and a content of 1,4-cis units of 35 to 85 mol%, particularly preferably of 45
to
85 mol%, and the glass transition temperature is below -60°C,
particularly
25 preferably below -70°C.
Vinyl aromatic monomers which undergo free-radical polymerisation alone or
optionally together with ethylenically unsaturated nitrite monomers and thus
form
the homogeneous phase (matrix phase) of the moulding compositions are the same
30 as those which were used to produce the rubber solution. Ring-substituted
chlorostyrenes may additionally be used as a mixture with said monomers.
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Ethylenically unsaturated nitrile monomers are preferably acrylonitrile and
methacrylonitrile, with acrylonitrile being particularly preferred.
Acrylic monomers or malefic acid derivatives may be used in a quantity of up
to
30 wt.%, preferably up to 20 wt.% of the total quantity of monomers: examples
are
methyl (meth)acrylate, ethyl (meth)acrylate, tert.-butyl (meth)acrylate,
esters of
fumaric acid, itaconic acid, malefic anhydride, malefic acid esters, N-
substituted
maleimides, advantageously such as N-cyclohexyl- or N-phenylmaleimide, N-alkyl-
phenylmaleimide, as well as acrylic acid, methacrylic acid, fumaric acid,
itaconic
acid or the amides thereof.
'The ratio of vinyl aromatic monomers to ethylenically unsaturated nitrile
monomers
in the ABS moulding compositions according to the invention is 60-90 wt.%
1 S 40-10 wt.%, relative to the matrix phase. The rubber content in the ABS
moulding
compositions according to the invention is 5-35 wt.%, preferably S-25 wt.%,
relative
to the ABS moulding composition.
The rubber content in the HIPS moulding compositions according to the
invention is
1 to 25 wt.%, preferably 3 to 1 S wt.%, relative to the HIPS moulding
compositions.
In the event that the free-radical polymerisation is performed in solvents,
solvents
which may be considered are aromatic hydrocarbons, such as toluene,
ethylbenzene,
xylenes and ketones such as acetone, methyl ethyl ketone, methyl propyl
ketones,
methyl butyl ketones and mixtures of these solvents. Ethylbenzene, methyl
ethyl
ketone and acetone, and mixtures thereof are preferred.
Polymerisation is advantageously initiated by free-radical initiators, but may
also be
performed thermally; the molecular weight of the resultant polymer may be
adjusted
by chain-transfer agents.
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Suitable initiators for the free-radical polymerisation are grafting-active
peroxides
which decay into free radicals, such as peroxycarbonates, peroxydicarbonates,
diacyl
peroxides, perketals or dialkyl peroxides and/or azo compounds or mixtures
thereof.
Examples are azodiisobutyric acid dinitrile, azoisobutyric acid alkyl esters,
tert.-
5 butyl perpivalate, tert.-butyl peroctoate, tert.-butyl perbenzoate, tert.-
butyl
perneodecanoate, tert.-butyl per-(2-ethylhexyl)carbonate. These initiators are
used in
quantities of 0.005 to 1 wt.%, relative to the monomers.
Molecular weights may be adjusted using conventional chain-transfer agents
such as
mercaptans, olefins, for example tert.-dodecyl mercaptan, n-dodecyl mercaptan,
cyclohexene, terpinols, a-methylstyrene dimer, in quantities of 0.05 to 2
wt.%,
relative to the monomers.
The process according to the invention may be performed discontinuously, semi-
continuously and continuously. In the continuous embodiment, the rubber
solution,
monomers and optionally solvents may advantageously be polymerised in the
first
stage in a continuously fed, mixed and stirred tank reactor at a steady-state
monomer
conversion after phase inversion of above 10% and the free-radically initiated
polymerisation may be continued in at least one further stage up to a monomer
conversion of 30-90% with mixing in one or more further continuously operated
stirred tanks connected in series or in a mixing plug flow reactor and/or a
combination of both types of reactor. Residual monomers and solvents may be
removed using conventional methods (for example in heat-exchange evaporators,
flash evaporators, strand evaporators, film evaporators, screw devolatilisers,
stirred
25 mufti-phase evaporators with kneading and stripping devices), wherein it is
also
possible to use blowing or entraining agents, for example steam, and returned
to the
process. Additives, stabilisers, antioxidants, fillers, lubricants may be
added during
polymerisation and during isolation of the polymer.
30 Discontinuous and semi-continuous polymerisation may be performed in one or
more filled or partially filled mixed stirred tanks connected in series, with
the rubber
WO 00/69940 CA 02372178 2001-11-15 PCTIEP00104032
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solution, monomers and optionally solvents being initially introduced and
' polymerised until the stated monomer conversion of 30-90% is achieved.
r
Mixing and dispersion of the introduced rubber solution may be improved by
continuously or discontinuously circulating the syrup through mixing and
shearing
elements. Such loop reactors are known prior art and may be of assistance in
establishing the particle size of the rubber. It is, however, more
advantageous to
arrange the shearing elements between two separate reactors, in order to avoid
back-
mixing, which results in a widening of the particle size distribution.
The average residence time is 1 to 10 hours, preferably 2 to 6 hours. 'The
polymerisation temperature is SO to 1$0°C, preferably 70 to
170°C.
The rubber-modified thermoplastic moulding compositions according to the
invention have rubber particle sizes of a diameter (weight average, dW) of 0.1-
10 Vim,
preferably of 0.1-2 ~m (ABS) or of 0.1-10 Vim, preferably of 0.2-6 ~m (HIPS).
The moulding compositions according to the invention may be melt processed to
form mouldings by extrusion, injection moulding, calendering, blow moulding,
pressing and sintering.
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Examples
Measurement methods
S The solution viscosity of the rubber solutions is measured on a S wt.%
solution using
a Brookfield viscosimeter at 25°C (Brookfield RV, SyncroLectric, model
LVT,
spindle 2, rotational speed settable, depending upon viscosity, to a fixed
speed of 6,
12, 30, 60 rpm).
ABS:
Conversion is determined by determination of the solids content by evaporation
at
200°C. The rubber content in the final product was determined from the
mass
balance. Gel contents were detenmined in acetone as the dispersant medium. The
intrinsic viscosity of the soluble fraction was determined with
dimethylformamide +
1 g/L of LiCI as solvent. The particle size and distribution were measured by
centrifugation as described in US 5,166,261; at variance with the stated
method, a
dispersion of the rubber particles in propylene carbonate was injected into a
mixture
of propylene carbonate/acetone (75:25); the weight average (dW), area average
(dA)
and number average (d") are stated. Notched impact strength (aK Izod) was
measured
at 23°C to ISO 180/1A and the melt volume index (MVI 220°C/10
kg) was
measured to DIN 53735. Phase structure was investigated by dynamic, mechanical
measurement of the shear modulus parameter G*(T) on the NKS unit at a
frequency
of approx. 1 Hz over a temperature range of -150 to 200°C using the
Rheometrics
RDA II. The glass transition temperature (Ts) of the soft phase and of the
matrix
were determined. The corrected shear modulus at 23°C was also
determined
(G'~ort.(RT)). The measurements were made on test specimens injection moulded
at a
melt temperature of 240°C and a mould temperature of 70°C.
HIPS:
Impact strength (aK-Izod) was determined at 23°C and -40°C to
ISO 180/1U, while
tensile strength, elongation at break, yield stress and modulus of elasticity
were
WO 00/69940 CA 02372178 2001-11-15 PCT/EP00104032
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determined to DIN 53 455 and DIN 53 457. The measurements were made on test
specimens injection moulded at a melt temperature of 200°C and a mould
temperature of 45°C. Thermelt volume index (MVI, 220°C, 5 kg)
was determined to
DIN 53 735.
S
Production of the rubber solutions
Polymerisation was performed under argon with exclusion of air and moisture.
Isolation of the polymers from the solution in styrene as described in some of
the
Examples was performed only for the purposes of characterising the polymers
obtained. 'The polymers may, of course, also be stored in the solution in
styrene
without being isolated and correspondingly further processed. The styrene used
as
solvent for polymerisation of the dime was stirred under argon over CaHz for
24
hours at 25°C and distilled off under reduced pressure at 25°C.
The styrene content
in the polymer is determined by 'H-NMR spectroscopy, while the selectivity of
the
polybutadiene content (1,4-cis, 1,4-trans and 1,2 content) was determined by
IR
spectroscopy and~the molecular weights were determined by GPC/light
scattering.
Examples A-E
Catalyst ageing A-C
5.3 g of butadiene, 1.88 ml of pentamethylcyclopentadiene and 217 ml of a 10%
solution of methylalumoxane in toluene (MAO) were added at 25°C through
a
septum to 38.4 ml of a 0.3125 molar solution of neodymium(III) versatate (NDV)
in
hexane in a 300 ml Schlenk tube, maintained at 50°C with stirring for 2
hours and
used for the polymerisation.
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Catalyst ageing D-E
6.0 g of butadiene, , 1,~ ml of indene and 217 ml of a 10% solution of
methylalumoxane in toluene (MAO) were added at 25°C through a septum to
49.0 ml of a 0.245 molar solution of neodymium(III) versatate (ND~ in hexane
in a
300 ml Schlenk tube, maintained at 50°C with stirring for 2 hours and
used for the
polymerisation.
Polymerisation
Polymerisation proceeded in a 40 L steel reactor with an anchor stirrer (50
rpm). A
solution of trimethylaluminium (TMA) or triisobutylaluminium (TIBA) in hexane
was added at room temperature as scavenger to a solution of butadiene in
styrene,
the reaction solution adjusted to a temperature of 50°C within 45
minutes and
combined with the appropriate quantity of catalyst solution. The reaction
temperature was maintained at 50°C during polymerisation. On completion
of the
reaction time, the polymer solution was transferred within 15 minutes into a
second
reactor (80 L reactor, anchor stirrer, 50 rpm) and polymerisation terminated
by
addition of 3410 g of methyl ethyl ketone with 7.8 g of p-2,5-di-tert.-
butylphenylpropionic acid octyl ester (Irganox 1076, Ciba Geigy) and 25.5 g of
tris-
(nonylphenyl) phosphite (Irgafos TNPP, Ciba Geigy). Unreacted butadiene was
removed by reducing the pressure within the reactor to 200 mbar within 1 hour
and
to 100 mbar within 2 hours at 50°C.
The following Table states the batch sizes, reaction conditions and properties
of the
resultant polymers.
WO 00169940 CA 02372178 2001-11-15 PCT/EP00/04032
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Example A B C D E
Catalyst solution 166 161 161 161 166
in m1_ ~
NDV in mmol 7.5 7.3 7.3 7.0 7.2
Polymerisation
Styrene in g 18070 16890 17154 16844 16777
Water content in ppm 83 30 37 12 31
1,3-butadiene in g 3003 3700 3703 3701 3700
TMA (2 molar) in ml 17 5.6 7 - 25.5
TIBA (2 molar) in - - - 73 -
ml
Temperature in C 50 50 50 50 50
Reaction time in h 4.5 3.25 3 3 4.5
Po_ lymer
Solids content in 16.31 16.29 15.51 19.2 12.3
wt.%
Styrene content in 25.8 15.6 13.6 12.4 11.5
mol%
Butadiene content 74.2 84.4 86.4 87.6 88.5
in mol%
1,4-cis in %'' S7 62 64 83 n.d.
1,4-trans in %'' 35 29 26 12 n.d.
1,2 in %" 8 9 10 5 n.d.
~ (5% in styrene) 46 59 78 55 148
in mPa~s
Ts in C -65 -72 -74 -90 n.d.
Mn in kg/mol 242 - - 165 n.d.
MW in kg/mol 332 - - 279 n.d.
Content of 1,4-cis, 1,4-trans and 1,2 units relative to butadiene content in
the
polymer.
n.d. = not determined
WO OOI69940 CA 02372178 2001-11-15 PCT/EP00/04032
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Production of ABS moulding compositions
Examples 1-7 r
S Solution I, consisting of rubber solution, styrene, acrylonitrile, methyl
ethyl ketone
(MEK), p-2,5-di-tert.-butylphenolpropionic acid octyl ester (Irganox 1076,
Ciba
Geigy) and alpha-methylstyrene dimer (AMSD) is mixed at 40°C with an
anchor
stirrer (150 rpm) in a 5 L flat-ground joint jar. Once this solution has been
heated to
82-85°C, the initiator solution II, consisting of methyl ethyl ketone
and tert.-butyl
perpivalate (t-BPPI~, is apportioned within 4 hours. The temperature is
controlled
throughout the reaction in such a manner that the mixture is gently refluxed
(82-
85°C). Two hours after the beginning of addition of solution II,
solution III,
consisting of methyl ethyl ketone and alpha-methylstyrene dimer, is added
within
1-2 minutes and then the stirrer is set to 100 rpm. Once addition of solution
II is
complete, stirring is continued for a further 2 hours at 85°C, then the
temperature is
reduced to RT. The mixture is stabilised by adding a solution of p-2,5-di-
tert.
butylphenolpropionic acid octyl ester (Irganox 1076, Ciba Geigy) and dilauryl
dithiopropionate (Irganox PS 800, Ciba Geigy) in methyl ethyl ketone. The
solutions
are then devolatilised in a laboratory twin screw devolatilising extruder and
pelletised. The pellets are injection moulded to form standard small bars.
The following Tables show the composition of the formulations, results of
polymerisation and characterisation of the ABS moulding compositions.
WO 00/69940 CA 02372178 2001-11-15 P~T~POO/~32
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Composition of the formulations (all values in g)
Example 1 2 3 4 5 6 7
Solution
I
Example 1287.6 1368.1- - - -
A
Example - - 1357.5 1261.7- -
B
Example - - - - 1413.5 1413.5
C
Example - - - - - - 1029.3
D
Irganox 0.40 0.43 0.43 0.40 0.40 0.40 0.40
1076
Styrene 359.9 295.1 313.9 313.9 254.0 160.9 366.5
Acrylonitrile427.1 423.9 427.1 427.1 427.1 395.3 395.3
MEK 225.4 212.9 201.4 297.2 205.4 330.4 509
AMSD 5.03 2.49 5.03 3.35 3.35 3.10 2.33
Solution
II
MEK 150 150 150 150 150 150 150
t-BPPIV 6.98 6.96 7.01 7.01 7.01 6.52 6.47
(75%)
Solution
III
MEK 50 50 50 50 50 50 50
AMSD 6.70 5.82 6.70 5.03 5.03 6.20 5.43
Solution
IV
MEK 250 250 250 250 250 250 250
Irganox 2.41 2.42 2.53 2.41 2.41 2.26 2.26
1076
Irganox 3.62 ~ 3.633.79 3.62 3.62 3.39 3.39
PS 800
' ' , WO 00/69940 CA 02372178 2001-11-15 PCTIEP00104032
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Results:
Example 1 2 3 4 5 6 7
Monomer conversion59.8 65.7 61.3 60.9 63.2 50.6 61.0
[%]
Rubber content 16.3 16.0 16.4 16.1 15.6 i9.9 17.2
in ABS [%]
Gel content [%] 26.9 29.9 29.9 30.2 31.0 35.5 31.1
Degree of grafting0.65 0.8680.821 0.875 0.985 0.7860.81
I
Intrinsic viscosity0.533 0.6400.545 0.575 0.585 0.5020.620
MVR (220C/10 kg) 4.1 2.5 2.8 2.2 1.8 1.7 2.4
[g/10']
dw [pm] 0.874 0.5360.603 0.592 0.838 0.8050.622
d" [pm] 0.335 0.2010.353 0.328 0.350 0.3580.281
dN [ItmJ 0.161 0.1090.161 0.157 0.145 0.1400.139
Characterisation of ABS moulding compositions
Example I 2 3 4 5 6 7
Notched impact 22.4 23.5 21.0 21.7 20.2 23.4 27.3
strength at
23C [kJImZJ
Tg, soft phase -62 -60 -70 -70 -72 -73 -88
[C]
Tg, matrix [C] 109 110 110 111 111 110 108
G'~",(RT) [MPaJ 880 865 800 790 755 660 790
Production of HIPS moulding compositions:
Example 8
The rubber solution from Example E is diluted to a solids content of 6% by
adding
styrene (stabilised). After addition of 0.5 parts by weight of Vulkanox MB~
and 0.2
parts by weight of a-methylstyrene dimer, 1200 g of this solution are purged
for 15
1 S minutes with N, in a 2 L glass autoclave with a helical ribbon stirrer.
The
temperature is raised to 120°C within 1 hour and the mixture stirred
(80 rpm) for 4.5
hours at this temperature. The resultant highly viscous solution is poured
into
' . WO OOI69940 CA 02372178 2001-11-15 PCTIEP00/04032
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pressure-resistant aluminium moulds and polymerised in accordance with the
following time/temperature programme:
r
2.5 h at 125°C
1.5 h at 135°C
1.5 h at 145°C
1.5 h at 165°C
2.5 h at 225°C.
After cooling, the polymer is comminuted and degassed under a vacuum for 20
hours at 100°C. Specimens for testing are injection moulded in an
injection
moulding machine. Mechanical values are determined on standard small bars.
Results:
Example
MVR (g/10'] 7.3
ak, 23C [kJ/mZ] ! 58.4
an, -40C [kJ/m'] 48.9
Tensile strength 37.5
[N/mm'] I
Elongation at break 45.2
[%]
Yield stress [N/mm']35.1
Modulus of elasticity2350
[MPa]
