Note: Descriptions are shown in the official language in which they were submitted.
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Use of inorqanic peroxide compounds for colour and/or heat
stabilisation of thermoPlastics cont~;n;n~ nitrile qroups
This invention relates to the use of inorganic peroxide
compounds or of mixtures thereof for colour and/or heat
stabilisation of thermoplastically processable polymers
containing nitrile groups or of blends thereof with
themselves or with other thermoplastics not containing
nitrile groups.
Polymer blends prepared from graft polymers of
acrylonitrile, ~-methylstyrene on acrylate rubber, a
rubbery copolymer prepared from acrylonitrile and alkyl
acrylate together with an uncrosslinked polymer of
styrenes, ~-methylstyrenes, acrylonitrile, meth-
acrylonitrile or esters of (meth)acrylic acid, together
with flexible polymer blends prepared from graft polymers
of a mixture of acrylonitrile and styrene on highly
crosslinked alkyl acrylate rubber, a graft polymer of
methyl methacrylate or a mixture of acrylonitrile and
styrene on highly crosslinked alkyl acrylate rubber and a
partially crosslinked rubbery copolymer prepared from
acrylonitrile, which are suitable for the production of
flexible, ageing resistant films with a leather-like
appearance and which may be processed by calendering and
thermoforming, are described in German published patent
applications DE-OS 38 11 899 and 37 43 489. The films
produced from the stated polymer blends exhibit a good
level of properties and have good ageing resistance. They
are, for example, used for automotive interior trim and, in
modified form, as furniture films. Despite their good
colour stability, even under the action of heat, in
comparison with hitherto customary film compounds
containing PVC, the films may be discoloured at elevated
processing temperatures and/or extended processing times,
particularly when in light shades, so rendering exact
colour shading or reproduction of light colours more
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difficult. There was thus a requirement for polymer blends
which have improved colour stability and so avoid the
stated disadvantages.
It has been found that the usual stabilisers customary for
PVC and/or ABS moulding compounds, such as alkyltin
mercaptides, phenolic or amine antioxidants, bring about no
improvement in colour stability in the above-stated polymer
blends. While the phosphites containing oxethane groups
described in EP 4 776 615 (US 5,196,466) do indeed lead to
better ageing stability, they cannot, however, completely
fulfil practical requirements for colour stabilisation. The
same also applies to the oligoepoxide compounds described
in EP 478 976 (US 5,229,455). While the stated oligoepoxide
compounds do indeed bring about a somewhat satisfactory
thermal stability and colour stability, they increase the
viscosity of the polymer blend so greatly that films cannot
be produced by extrusion and calendering is rendered much
more difficult.
There thus still remains a requirement for additives which
improve the colour and/or thermal stability of certain
thermoplastics which have a tendency to discolour during
processing. The present invention thus provides the use of
inorganic peroxide compounds or of mixtures thereof for
colour and/or heat stabilisation of thermoplastically
processable polymers containing nitrile groups or of blends
thereof with themselves or with other thermoplastics not
containing nitrile groups.
Tnorganic peroxide compounds suitable ~or the stated
application which may, in particular, be cited are:
sodium peroxide, barium peroxide, salts of the peroxo
acids, such a potassium peroxodisulphate, potassium
perchlorate, salts with crystalline hydrogen peroxide, such
as sodium perborate, salts of perchloric acid, such as
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potassium perchlorate, salts of persulphuric acid, such as
potassium peroxodisulphate, peroxoborates, such as sodium
peroxoborate, preferably salts of perchloric acid, salts of
persulphuric acid, peroxoborates, very particularly
preferably potassium perchlorate and sodium peroxoborate.
As already stated, the inorganic peroxide compounds may be
added to the thermoplastically processable polymers
containing nitrile groups both alone and mixed together. If
mixtures of peroxide compounds are used, their mixture
ratio is not critical. The optimum mixture ratio may
readily be determined by appropriate preliminary testing.
Desensitisation of the peroxide compound with inert
substances is, however, generally necessary.
The inorganic peroxide compounds are added to the
thermoplastics in quantities of 0.01 to 8.0 wt.~,
preferably of 0.1 to 3.0 wt.~, very particularly preferably
of 0.2 to 2.0 wt.~, relative to the quantity of
thermoplastics used.
The following polymers may be considered as
thermoplastically processable polymers containing nitrile
groups which may be colour and/or heat stabilised according
to the invention with the inorganic peroxide compounds:
acrylonitrile/butadiene/styrene graft polymer (ABS),
nitrile/butadiene rubbers (NBR),
acrylonitrile/styrene copolymer (SAN),
acrylonitrile/styrene/acrylic ester copolymer (ASA),
methyl methacrylate/acrylonitrile copolymer (AMMA),
polyacrylonitrile (PAN),
preferably (ABS), (ASA) and (NBR), very particularly
preferably (ABS) and (ASA).
The stated thermoplastics may be used both alone and as
blends with themselves or blends with other thermoplastics
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not containing nitrile groups. Thermoplastics not
containing nitrile groups which may, for example, be
considered are:
methyl methacrylates, polycarbonates, polyesters, ethylene
vinyl acetates, polystyrenes, preferably ethylene vinyl
acetates and polycarbonates.
The thermoplastics not containing nitrile groups may be
added to the thermoplastics containing nitrile groups in
quantities of 5 to 95 wt.~, preferably of 5 to 40 wt.~,
relative to the total quantity of polymer.
The above-mentioned thermoplastically processable polymers
containing nitrile groups and the thermoplastics not
containing nitrile groups are known and described in
greater detail, for example, in Kunststoff-Handbuch,
R. Vieweg, Carl Hanser Verlag Munich, 1969, volume 5;
Kunststoff-Handbuch, R. Vieweg, Carl Hanser Verlag Munich,
1973, volume 8; Kunststoff-Handbuch, R. Vieweg, Carl Hanser
Verlag Munich, 1975, volume 9; Kunststoff-Handbuch,
R. Vieweg, Carl Hanser Verlag Munich, 1969, volume 4;
Kunststoff-Handbuch, R. Vieweg, Carl Hanser Verlag Munich,
1966, volume 6.
Once sufficiently desensitised, the inorganic peroxide
compounds according to the invention may be incorporated
into the thermoplastically processable polymers containing
nitrile groups which are to be stabilised in devices
customary for this purpose, such as high speed mixers,
kneaders or extruders. The colour and/or heat stabilised
thermoplastically processable polymers containing nitrile
groups may be used to produce mouldings of all kinds, and
to produce film. Use for the production of films is
particularly preferred.
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Examples
Example 1
A polymer blend of 90 parts of an acrylonitrile/styrene/
butyl acrylate copolymer, 10 parts of an ethylene/vinyl
acetate copolymer, 0.3 parts of lubricant and the
stabilising compounds stated in table 1 is produced in a
roll mill. Thermal stability is tested by rolling at 200C
and by exposure to a temperature of 200C in a Mathis oven
and visually assessed by means of any possibly occurring
colour changes.
Table 1 Additions to polymer blends (in parts by weight),
relative to 100 parts by weight of the initial
moulding compound
Stabilising compoundParts by weightHeat treatment Findings
(%) t200C)
Barium peroxide 0.20 roll mill No discoloration for
~desensitised) up to 30 minutes
Potassium perchlorate 0.20 roll mill No discoloration for
(desensitised) up to 30 minutes
Potassium perchlorate 1.00 roll mill No discoloration for
(desensitised) up to 30 minutes
Sodium peroxoborate2.00 roll mill No discoloration for
up to 30 minutes
Potassium perchlorate 0.10 oven No discoloration for
(desensitised) up to 20 minutes
Potassium perchlorate 1.00 oven No discoloration for
(desensitised) up to 20 minutes
Sodium peroxoborate2.00 oven No discoloration for
up to 20 minutes
Tris(3-ethyl-3-methylol-2.00 oven No discoloration for
oxethane)phosphite up to 10 minutes
Epoxy resin based on2.00 oven No discoloration for
bisphenol A and up to 10 minutes
3 5 epichlorohydrin
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Comparative examples
Comparison polymer blends are produced in a similar manner
to the examples without the component containing peroxide.
While the comparison moulding compounds discoloured to pale
brown after only 10 minutes at 200C and to dark brown
after 20 minutes, the examples containing peroxide
exhibited no substantial change in the natural hue after 20
or 30 minutes.
Example 2
A polymer blend of 90 parts of an acrylonitrile/butadiene/
styrene graft polymer, 10 parts of ethylene/vinyl acetate
copolymer, 0.2 parts of Makrolex Blau RR (from Bayer AG),
0.3 parts of lubricant and the stabilising compounds stated
in table 2 was prepared in a roll mill. Thermal stability
is tested by exposure to a temperature of 200C in a Mathis
oven and visually assessed by means of any possibly
occurring colour changes.
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Table 2 Additions to polymer blends (in parts by weight),
relative to 100 parts by weight of the initial
moulding compound
Stabilising compoundParts by weightHeat treatment Findings
~%) (200C)
Potassium perchlorate0.20 oven No discoioration for
(desensitised) up to 20 minutes
Potassium perchlorate1.00 oven No discoloration for
(desensitised) up to 20 minutes
Sodium peroxoborate 2.00 oven No discoloration for
up to 20 minutes
Tris(3-ethyl-3-methylol-2.00 oven No discoloration for
oxethane)phosphite up to 10 minutes
Epoxy resin based on2.00 oven No discoloration for
bisphenol A and up to 10 minutes
epichlorohydrin
Triglycidyl isocyanurate 1.00 oven No discoloration for
up to 20 minutes
Comparati~e examPles
Comparison polymer blends are produced in a similar manner
to the examples without the component containing peroxide.
While the comparison moulding compounds discoloured to
light blue after only 10 minutes and to dark blue after 20
minutes, the examples containing peroxide exhibited no
change in the blue shade after 20 minutes.
Example 3
A polymer blend of 70 parts of an acrylonitrile/butadiene/
styrene graft polymer, 30 parts of a polycarbonate, 0.3
parts of lubricant and the stabilising compounds stated in
table 3 is prepared in a roll mill. Thermal stability is
tested by exposure to a temperature of 200C in a Mathis
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oven and visually assessed by means of any possibly
occurring colour changes.
Table 3 Additions to polymer blends (in parts by weight),
relative to 100 parts by weight of the initial
moulding compound
Stabilising compoundParts by weightHeat treatment Findings
(%) (200C)
Potassium perchlorate0.20 oven No discoloration for
(desensitised) up to 10 minutes
Potassium perchlorate1.00 oven No discoloration for
(desensitised) up to 20 minutes
Sodium peroxoborate 2.00 oven No discoloration for
up to 20 minutes
Comparative examPles
Comparison polymer blends are produced in a similar manner
to the examples without the component containing peroxide.
While the comparison moulding compounds discoloured to
light brown after only 10 minutes and to dark brown after
20 minutes, no change in the natural hue occurred in the
examples after 10 or 20 minutes.
Example 4
A polymer blend of 70 parts of an acrylonitrile/butadiene/
styrene graft polymer, 20 parts of a nitrile/butadiene
rubber, 10 parts of a styrene/acrylonitrile copolymer,
0.3 parts of lubricant and the stabilising compounds stated
in table 4 is prepared in a roll mill. Thermal stability is
tested by exposure to a temperature of 200C in a Mathis
oven and visually assessed by means of any possibly
occurring colour changes.
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Table 4 Additions to polymer blends (in parts by weight),
relative to 100 parts by weight of the initial
moulding compound
Stabilising compoundParts by weightHeat treatment Findings
(%) (200C)
Potassium perchlorate0.10 oven No discoloration for
(desensitised) up to 10 minutes
Sodium peroxoborate 2.00 oven No discoloration for
up to 10 minutes
Comparative examPles
Comparison polymer blends are produced in a similar manner
to the examples without the component containing peroxide.
While the comparison moulding compounds discoloured to
light brown after only 10 minutes at 200C and to dark
brown after 20 minutes, no change in the natural hue was
observed in the examples according to the invention after
10 minutes and a slight brown coloration occurred after 20
minutes.
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