Note: Descriptions are shown in the official language in which they were submitted.
CA 02347260 2006-09-25
POLYAMIDE COMPOSITION STABILIZED WITH COPPER SALT
AND AN AROMATIC HALOGEN COMPOUND
The present invention relates to stabilized polyamide compositions.
Polymers are degraded easily when heated by oxidation, which leads to
embrittlement of
the material and to mechanical failure of the products produced therefrom.
Therefore
particular chemical compounds are added which can delay the time of
embrittlement with
different activity. These so-called antioxidants are mostly built on the basis
of phenyl
derivatives, amine derivatives or phosphorous derivatives. Specific variants
of
antioxidants are employed with polyamides. One in particular active class of
compounds,
which does not have any activity with other polymers, are the so-called copper
stabilizers.
These types of stabilizing systems are long known and are used widely for the
preparation of polyamides, for examples for polyamide filaments which are used
for the
production of tyre cord and for polyamide extrusion molding parts for
technical
employment, in particular in the area of technical engineering (automobiles)
and the
electronic industry (switches, printed circuit boards).
These copper stabilizers usually consist of two components. As a first
component, a
compound such as copper halide or other copper salts are employed. In order to
be
effective as antioxidants, as second component a halogen compound must be
added in a
large surplus. Used in this respect are in particular potassium iodide and
also potassium
bromide. The employed molar ratio of copper to halogen is typically 1:5-15.
The
recommended amount is generally 30 to 200 ppm copper and accordingly 150 to
3,000
ppm halogen.
These copper stabilizers do show somewhat satisfying results with polyamides.
However, these commonly employed copper stabilizers do show some severe
drawbacks.
CA 02347260 2002-04-05
z
Polyamides take up (conditioning) approximately 3% water. If the temperature
changes
water soluble components are extracted from the polyamide to the surface,
which leads
to the formation of scale. If copper halides, potassium halides or other
soluble halides
are employed these will be extracted to the surface and will form a
hygroscopic scale
which will react mostly acidic. Therefore the tracking resistance will
decrease- Wlth
electric components this may lead to failure. If eontact with metals is given
the contact
places will endure increased corrosion. Requirements of the electronic
industry and the
automobile industry regarding the question of tracking resistance are
therefore difficult to
fulfil.
At the same time these stabilizers are diffilcult to disperse in the
polyamide. When
preparing stabilized polyamides it is important to make sure that the employed
stabilizers
are finely powdered and can be admixed with the polyamide very homogeneously.
On
problem associated therewith is usually the tendency of the usually employed
components to agglomerate. The raw materials must therefore be ground very
finely and
must be protected against reagglomeration. The addition Itself is usually very
difficult to
control, therefore usually a master batch will be produced which will be
added. Even
then such a heterogeneous mixture of solid particles in a melt Is never
optimal,
compared with the hypothetical case that the stab~Iizer itself would be
meltable and could
be dispersed homogeneously under working conditions, as is the case with
phenoic,
amine and other antioxidants. The crystalline partiGes of the stabilezer salts
effect the
physical properties of the polyamides negative, even if they ors finely
dispersed. This
does not only result from possible inhamogeneity but also from the fact that
fine particles
aci as crystallisation nuGei which result in a higher crystallinity in
polymers. This can
lead to negative side effects. The impact strength can for example decrease by
20 to
30%, compared with the initial value of the non-stabilized polyamide.
Usual stabilizing compounds furthermore lead in polyamides after conditioning
often to a
bluish or greenish discoloration. Polyamldes reinforced with fiber glass may
furthermore
show a brown coloration due to the formation of copper oxide, resulting from
high sheer
stress given during processing. In particular negative are variations of the
discoloration
during the production cycles, which will make the use of the produced
materials for non-
colored or colored products difiticult. Therefore such polyamldes are usually
employed
after black coloration.
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3
Usual stabilizing compounds are often added during the polymerization as
aqueous
solution in order to optimise the dispersion. One drawback is however that
this addition
may lead to formation of state of metallic copper or of copper oxide on the
metal surface
of the employed vessels and melt extruders. This may lead to variation in
coloration and
therefore to the discontinuation of the production. During spinning of
filaments scale
formation at the nozzle is often encountered which will lead to the
discontinuation of the
process.
In view of these drawbacks several improvements were proposed.
EP-A-39o2T! discloses a stabilized polyamide 4.6 composition- This particular
high
melting point polyamfde can be stabilized by addition of an unsoluble copper
salt and a
halogen substituted organic compound. These compositions are suitable for
electric or
electronic uses.
GB-A-1131933 and GB-A-1143826 disclose stabilized linear polyamides,
stabilized with
a mixture of a copper compound, soluble in the polyamide, and a specific
halogen
containing organic aliphatic compound with at most 7 carbon atoms. These
organic
compounds have however a high volatility. This may lead to undesired
embrittlement of
the material due to how out of the organic compound.
Starting from the above described problems associated with the prior alt it is
therefore
the object of the present invention to provide a stabilized polyamide
composition which
does not show the above named drawbacks, while simultaneously improving the
long
term temperature stability.
This object is solved in accordance with the present invention by the
provision of a
stabilized polyamide composition, characterized in that as stabilizer at least
one copper
salt and at least one organic halogen containing compound Is contained,
selected
among the group consisting of (a) aromatic compounds ; (b) aliphatic
phosphates; (c)
paraffins; or mixtures thereof, with the proviso that if the aromatic compound
is a bromine
containing styrene oligomer the polyamide is not polyamide 4.6.
Surprinsingly it was found that such stabilized polyamide compositions do show
improved properties and an increased long term temperature stability.
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Furthermore the present invention provides a process for the preparation of a
stabilized
polyamide composition, comprising the mixing of at least one polyamide, at
least one
copper Bait and at least one organic halogen containing compound selected
among the
group consisting of (a) aromatic compounds ; (b) aliphatic phosphates; (c)
paraffins; or
mixtures thereof, with the proviso that if the aromatic compound is a bromine
containing
styrene oligomer the polyamide is not polyamide 4.6.
Furthermore the present invention provides the use of at least one copper salt
and at
least one organic halogen containing compound, defined as given above, for the
stabilization of polyamida compositions.
Prefered are each time compounds (a) andlor (b).
The at least one pvlyamide in accordance with the present Invention may be any
polyamide. Polyamides are polymers showing recurrent carbon amide groups -CO-
NH-
in the polymer backbone. Polyamides are made from
(a) amino cart~oxylic acids and their functional derivatives, for example
lactames; or
from
(b) diamines and dlcarboxylic acids or their functional derivatives.
By varying the monomer units polyamldes are obtainable in a broad variety. In
accordance with the present invention all polyamfdes may be stabilized, for
example
copolyamides or homopolyamides. Usable are furthermore block copolymers of
polyamides and polyethers and other polymer modified polyamides. The most
common
types are polyamide 6 from e-caprolactam and polyamide BB from hexamethylene
diamine and adipidic acid. Other important polyamides are potyamide 610,
pofyamide 11,
polyamide 12, PACM-12 , MPB-I, PPD-T and the aramides_
It is furthermore possible to use blends of polyamides with other polymers.
How ever, the
stabilizing compounds may excert negative effects with respect to the blend
components.
Therefore these most be chosen carefully.
In accordance with the present invention any copper salts may by used.
CA 02347260 2002-04-05
Preferred are salts of mono- or divalent copper with inorganic or organic
acids. Examples
of suitable copper salts are copper (I) salts, such as CuJ, CuCI, ar GuGN,
copper (II)
salts, such as CuCl2, CuBr2, Cu-acetate, Cu-sulfate, Cu-stearate, Cu-
propionate, Cu-
butyrate. Cu-lactate, Cu-benzoate or Cu-nitrate, as well as ammonium complexes
of the
above given salts.
Furthermore compounds such as Cu-acetylacetonate or Cu-EDTA may be employed.
It
is furthermore possible to use mixtures of different copper salts. Optional Cu
powder may
be used. This reacts with poiyamlde melts under formation of copper compounds.
Preferred are Cu (I) halides and Cu-salts of organic acids, in particular
preferred are CuJ
and Cu-acetate.
The amount of copper , used in the stabilized polyamlde compositions is not
limited, as
long as the mechanical properties of the polyamide are not affected
detrimental. Usually
the amount is between 10 and 1000 ppm copper, based on the total composition.
Preferably 20 to 700, in particular 50 to 150 ppm copper are employed.
As organic halogen containing compound of the invention any aromatic andlor
any
aliphatic phosphate andlor any paraftln may be employed. Preferred are
aromatic
bromine containing compounds, bromine containing aliphatic phosphates and
chlorine or
bromine containing paraffines. The molecular weight of the employed compounds
of the
invention is not limited. It should be selected so that the compount is not
too volatile, the
compound can be mixed easily and homogeneously with the polyamide and shows
only
minor migration tendency In the final composition. Preferred are further
bromine
containing aromatjc oltgomeric epoxy resins, in particular compounds on the
basis of
tetrabromobisphenol-a.
Examples of usable paraffins era halogenated, in particular fluorinated,
chlorinated or
brominated paraffins. Usable are furthermore soft as well as hard paraffins.
Preferred are
compounds such as chloroparaffins (for example with an average formula of
CzaH=aCl,s ),
teflon waxes (for example with an average formula of CzoH~FZO) and Viton
copolymers
(copolymers of hexafluoroprapylene and vinylidene fluoride).
Examples of suitable compounds are-
CA 02347260 2002-04-05
6
Tris-{neobromopentyl)phasphate (phosphate 1), dibromodfoxaphosphorinane
derivatives
and chlorine containing polyphosphonates and dekabr~omophenyl,
dekabromophenylether, polydibromostyrene, tetrabromoblsphenol-A, chlorinated
and
brominated styrene oligomers, tetrabromobisphenol-A-derivatives, such as
8EB500C
(EP-ollgomer 1) and BEB6000 (EP-oligomer 2), which structures are given below,
and
chlorinated dimethanidibenzo(a,e)cacloocten-derivatives. Preferred are tris-
(dibromoneopentyi)phosphate and dekabromophenyl and polydibromostyrene. It is
furthermore possible to use mixtures of organic halogen containing compounds.
The addition amount of the halogen containing organic compound is usually
below 10
wt°!°_ Typically such amounts are added so that 50 to 30,000 ppm
halogen are present,
preferably 100 to 10,000 ppm, snare preferably 500 to 7 500 ppm, based on the
total
composition.
accordingly usually a ratio of copper to halogen In the stabilized polyamide
compositions
of from 1:1 to 1:3000 is obtained. Preferred is the area from 1.2 to 1:100, In
particular
the range from 1:5 to 1:15 (based on the molar ratio).
Higher addition amounts usually do not lead to an increase of the
stabilization effect,
poiyamides containing more than 5~° organic halogen containing
compounds do have a
significant lower stability. They show increased cleavage of polymer chains,
which leads
to premature embrittlement of the products and to strong discoloration.
Preferably the
content of organic halogen containing compound is less than 3 wt%, in
particular less
than 1 wt%.
The above defined copper salts and organic halogen containing compounds w~l ~
be
named stabilizer components in the following.
Polyamlde compositions in accordance with the present invention show improved
long
teen temperature stability, improved tracking resistance and lower
discoloration. These
advantages of the compositions of the present invention are deemed to be due
to the
synergistic effect of the organic halogen containing compounds, which must be
added in
minor amounts only.
CA 02347260 2002-04-05
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The tracking resistance, which is determined as CTI-value is improved greatly
with the
use of the organic compounds. Accordingly the area of practice for the
polyamide
composi~ons in accordance with the invention is broadened to produces which
are used
in the electro or electronic industry.
Polyamides for electrical products should possess CTI-values of 600, at least
however of
550. This value is reached with pure polyamide. The CTI-value is determined in
accordance with DIN-IEC 112.
The polyamide compositions in accordance with the present invention further
show,
compared with usual copper/halogensalt-stabilizers, improved electrical
strength.
The used organic compounds show, compared with halogen salts an improved
dispersion ability in the polymer melt. Therefore a complicated homogenisation
can be
omitted. If at the same dme a copper salt such as copper stearate is employed,
the
stabilizer itself is meltable and therefore easy to disperse in the polyamide_
The stabilizing components are compatible with ail sorts of pofyamines.
Therefore
blooming at the processing apparatuses (nozzles, extruders, molds) and the
produced
parts and filaments does not occur.
Furthermore the polyamide compositions in accordance with the present
Invention do
show only very limited tendency towards discoloration. In particular wit
fiberglass
reinforced polyamides with conventional copper stabilizers discolorations were
sv strong
that these compositions wefe only usable after black coloration. It is
therefore surprising
that this discoloration occurs with the polyamide compositions according to
the present
invention only to a minor extent, if at all. It is possible to obtain
compositions colored with
pigments without color deviations- Even TiOz colored compositions maintain the
clear
white color. This opens a new application field for colored polyamides in
areas where
improved long term thermal stability is required, so long only obtainabiy with
common
stabilizers having the drawback of strong discoloration.
The polysmide compositions in accordance with the present invention therefore
have the
advantage of fmprovef long term temperature stability while being at the same
time
colorable with pigments, without the danger that the usual own discolorations
alter the
pigment coloration.
CA 02347260 2002-04-05
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For coloration of the polyamide composmons in accordance with the present
invention
all common pi~ments are suitable, such as titandloxld~, lead white, zinc
white, lipone,
antimony white, carbon black, iron black, mangan black, cobalt black, antimony
black,
lead chromate, mennige, zinc yellow, zinc green, cadmium red, cobalt blue,
Berlin blue,
ultramarine, mangan violet, cadmium yellow, schweinfurt green, molybdenum
orange,
molybdenum red, chromium orange and chromium red, iron oxide red, chromoxide
green, strontium yellow, chromoxidr~ green, molybdenum blue, chalk, acker,
umbra,
green soil, terra dl sienna and graphite_
The poiyamide compositions in accordance with the present invention are
furthermore
excellent concerning theft stability regarding hydrolysis. They show improved
long term
stability under acidic and basic conditions, vis-a-vis salt solutions, glycol
water mixtures
and hot fats and oils and organic solvents. Accordingly, the usually
recognised decrease
of mechanical strength (impact strength, tensile strength) and the tendency
towards
embrittlement of the poiyamides is drastically reduced and the long term
durability
enhanced. Compared with usually employed stabilizers, such as phenolic or
amine
compounds or common copperfialogen salt-stabilizers, improved effects are
obtained.
The polyamide compositions in accordance with the present inventJon can
furthermore
be combined without limitations with further additives, such as lubricants,
plasticiters,
crystallization accelerators and pigments without detrimentally effecting the
desired
stabilization effect. In some cases even the used additives are stabilized
against thermal
decomposition or discoloration in polyamides. Therefore, polyamides mixed with
plasticizers, such as BBS, or with waxes, such as montanates, no longer show a
high
tendency to ageing, when employed in polyamide compositions In accordance with
the
present invanticn.
Poiyamldes containing glass bowls, fiber glass, mineral additives or other
reinforcing
agents furthermore show, compared with common stabilizers, a significantly
improved
long-term thermal ageing stability.
The polyamide compositions in accordance with the present invention may
contain
furthermore usual fillers and reinforcing agents. Examples of suitable fillers
and
relnforsing agents are glas materials In the form of fibers, ravings, beads or
powders,
CA 02347260 2002-04-05
9
oxidic materials, such as sflics, alumina or aluminum silicates as well as
graphite or
plastic fibers or whiskers.
The above described advantages of the polyamlde compositions of the pres~nt
invention
make it possible to use them for the preparation of fibers and for parts in
the electric or
electronic industry, mainly plug-in parts, plates (supports for electric
r~~ntacts) and casing
parts.
Furthermore, the stabilized polyamide compositions in accordance with the
present
invention were evaluated in order to deteimlne whether any further improvement
of the
discoloration tendency could be achieved. Surprisingly, it was found that a
further
reduction of the discoloration could be achieved by the addition of organic
phosphites or
inorganic phosphonates or inorganic hypophosphltes. These substances ara known
as
color stabilizers in polyamides. It was, however, also known that these color
stabilizers
could lead ofken to the formation of copper oxides with copper salts.
Therefore, a grey
discoloration or brown/ black discolorations occurred. Therefore, it was
surprising that
the combination in accordance with the present inv~ntlon does not lead to any
discoloration and that, furthermore, the blue discoloration, occurring
sometimes after
conditioning could be reduced by the addition of organic phosphites ar
inorganic
phosphonates or inorganic hypophophites. The slight discoloration occurring
during this
mixing can be cross dyed for the preparation of color stable polyamides,
It was furthermore found that this addition furthermore retards the ageing of
the
polyamides during thermal storage. This effect is particularly significant
with organic
phosphates.
The employable organic phosphates are esters of the phosphoric acid.
Employable are
aliphatic as well as aromatic or mixed esEers. Typical examples are, for
example,
dimethyl and diethyl phosphlte, trimethyl and methyl phosphate as well as the
additives
known in the plastic processing Industry. Typical examples are Tris(2,a-dl~t-
butylphenyl)phosphite (Phosphate 20), Bis(2,4-di-t-
butylpheny!)pentaerythritoldi-phosphate
(Phosphate 21 ), Tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylendiphosphonite
(Phosphate
23), Dlstearylpentaerythritoldiphosphite, Diisoactylphosphite,
Distearylphosphite,
Triisodecylphosphlte, Triisooctylphosphite, Trilaurylphosphite,
Tristearylphosphite,
Tris(dipropylenglycol)phosphlte, Diphenylphosph~te, Trisnonylphenyfphosphite,
Triphenylpho5phite, Trls(p-nonylphenyl)phosphite. These compounds are
available
CA 02347260 2002-04-05
under the tradenames Irgafos, Alkanox and Weston from the companies Ciba,
Weston
and The Great Lakes. Preferred are, in peritcular, Phosphate 20, Phosphate 21,
Phosphate
22 and Phosphate 23.
Usable inorganic phosphonates are salts of the phosphonic acid. Employable as
salt
builders are alkali metals, earth alkali metals and ail other usual metals.
Preferred are, in
particular, lithium, potassium, sodium, magnesium, calcium, strontium, barfum
and
aluminum, in particular preferred are sodium, potassium, magnesium and
calcium. A
preferred phosphortate is disodium hydrogen phosphonate.
The usable inorganic hydrophosphltes are salts of the hypophosphortc add.
Concerning
the salt building, it Is referred to the above metals listed in connection
with the inorganic
phosphanates. The sodium salt of the hypophosphoric acid is a preferred
example of the
employable hypophosphites_
The addition amount of the above given additives is between 0.005 and 1.0% (50
to
10,000 ppm), preferably from 0.05 to 0.2% (500 to 2000 ppm) and in particular
preferably
from 0.075 to 0.15% (750 to 1500 ppm). These amounts relate everytime to the
total
composition.
The organic phosphltes to be used are preferably mekable, processing stable
and stable
against extraction. This ensures that no phosphoric acid will be cleaved which
may have
disadvantageous effects for the total composition. The above given organic
phosphltes,
in particular the Phosphates 20, 21, 22 and 23, satisfy the requirements
excellently.
Therefore, these compounds are particularly preferred.
It has, furthermore, been recognised during the preparation of the stabilized
polyamide
compositions in accordance with the present invention that the addition of the
organic
phosphate, the inorganic phosphonates and the inorganic hypophosphites should
preferably occur only after the preparation of the basic composition
stabilized with the
stabilizing components.
If a stabilized polyamide composition in accordance with claim 1 is produced
first and if
the organic phosphate, the inorganic phosphonate or the inorganic
hypaphosphite is
added only thereafter during an additional step, no discoloration occurs. The
above
described procedure is in particular efPeciive with inorganic phosphonates.
The organic
CA 02347260 2002-04-05
11
phosphite, the inorganic phosphonate or the inorganic hypophvsphite can be
added as
such or In the form of a masterbatch. Concerning the masterbatch technology it
is
referred to the previous disclosure in this respect, the same principles are
valid here.
The production of the polyamide compositions is carried out usually by mixing
at least
one polyamide with at least one copper compound and at least one halogen
containing
compound, selected as defined in claim 1.
It is possible to mix the components using.common apparatuses, namely
polyamide and
stabilizing compounds are mixed with one another and are fused. It is
preferred,
however, to first fuse the polyamide and to mix in subsequently the
stabilizing
components. It is even more preferred to add the stabilizing compound in the
form of a
master batch to the molten polyamide. This simplifies in particular the
metering of the
stabilizing components.
Suitable mixing apparatuses are known to the person skilled in the art and
comprise
mixing rollers, discontinuous kneaders, continuous extruders and kneaders and
static
mixers. Preferred is the use of continuous extruders, single screw extruders
as well as
double screw extruders, which allow a good mixing. Usually the polyamide will
be fused
in the extruder, the stabilizing component can be metered in later through
suitable
openings. This process as well as the apparatuses for these purposes are known
to the
person skilled in the art.
It is furthermore possible to add the stabilizing components during the
production of the
polyamides, for example by adding them to the monomer mixture. This leads to a
very
good dispersion without any further mixing step which reduces the production
costs and
the production time.
If a master batch of the stabilizing components is used for the production of
the
polyamide compositions in accordance with the present invention, the master
batch can
be produced in discontinuous mixers which allow a very good homogenous mixing,
for
example a Buss-kneader. However, usually continuous mixers are used such as
double
screw extruders or ZSK-extruders. The matrix material ampioyed is usually the
same
polyamide which will b~ mixed later with the master batch It is, however, also
possible to
usa another polyamide or another polymer. The concentrakion of stabilizing
components
depends from the compatability of the matrix material and from the desired
final
concentration in the final blend and from good metering ability. Masterbatches
with
CA 02347260 2004-02-04
12
concentrations up to 50% can be obtained, for example from a mixture of CuJ
and
polydibromostyrene (1:10).
In the following some preferred combinations of copper salts and organic
halogen containing compounds are given.
Copper compound Organic halogen compound
CuJ Tris-(tribromoneopentyl)phosphate
CuJ 1,2,3-indioxaphosphorinane-5,5-
bis(bromomethyl)-2-methoxy-2-oxide
CuJ Polydibromostyrene
CuJ Dekabromophenylether
CuCl2 Tris-(tribromoneopentyl)phosphate
Cu-acetate Tris-(tribromoneopentyl)phosphate
Cu-acetate Tris-(tribromoneopentyl)phosphate
Cu-acetate EP oligomer 2
CuJ EP oligomer 1
CuJ Dechlorane plus
CuJ Chloroparaffin av. C20H24C118
CuJ Teflon wax av. C20H22F20
Cu (II) stearate Phosphate 1
The Ep oligomers in particular possess high temperature stability. Furthermore
their combinations with copper compounds are cheap.
Polydibromostyrene and EP oligomer 1 are suitable for the preparation of
highly concentrated masterbatches. Masterbatches up to 50% of these
compounds can be prepared.
EP oligomer 2 can only be introduced up to 10%. Due to a reaction of the EP-
end groups with amino groups in the polyamide a strong increase of the
viscosity is encountered. This chemical reaction however has the advantage
that the dispersion and bonding in the final product is increased.
CA 02347260 2005-05-04
12a
In another aspect, the present invention provides use of at least one copper
salt
and at least one organic halogen containing compound for the stabilization of
polyamides, wherein the organic halogen containing compound is selected among
the group consisting of: (a) aromatic compounds; (b) aliphatic phosphates; and
(c)
paraffins; or mixtures thereof, with the proviso that, if the aromatic
compound is a
brominated styrene oligomer the polyamide is not polyamide 4.6, and with the
proviso that the organic halogen containing compound is not an iodide
containing
compound.
In another aspect, the present invention provides a polyamide composition,
characterized in that as stabilizer at least one copper salt and at least one
organic
halogen containing compound are contained, wherein the organic halogen
containing compound is selected among the group consisting of: (a) aromatic
compounds; (b) aliphatic phosphates; and (c) paraffins; or mixtures thereof,
with the
proviso that, if the aromatic compound is a brominated styrene oligomer the
polyamide is not polyamide 4.6, and with the proviso that the organic halogen
containing compound is not an iodide containing compound, wherein said copper
salt is in an amount of 10 to 1,000 ppm, wherein said organic halogen is in an
amount of 50 to 30,000 ppm, and wherein said paraffins comprise 7 or more
carbon
atoms.
In another aspect, the present invention provides a method for the preparation
of a
stabilized polyamide composition, characterized in that at least one
polyamide, at least
one copper salt and at least one organic halogen-containing compound, selected
among the group consisting of: (a) aromatic compounds; (b) aliphatic
phosphates; and
(c) paraffins; or mixtures thereof are mixed with one another, with the
proviso that, if
the aromatic compound is a brominated styrene oligomer the polyamide is not
polyamide 4.6, and with the proviso that the organic halogen containing
compound is
not an iodide containing compound, wherein said copper salt is in an amount of
10 to
1,000 ppm, wherein said organic halogen is in an amount of 50 to 30,000 ppm,
and
wherein said paraffins comprise 7 or more carbon atoms.
In another aspect, the present invention provides use of at least one copper
salt and at
least one organic halogen containing compound for the stabilization of
polyamides,
CA 02347260 2005-05-04
12b
herein the organic halogen containing compound is selected among the group
consisting of: (a) aromatic compounds; (b)aliphatic phosphates; and (c)
paraffins;
or mixtures thereof, with the proviso that, if the aromatic compound is a
brominated
styrene oligomer the polyamide is not polyamide 4.6, and with the proviso that
the
organic halogen containing compound is not an iodide containing compound,
wherein
said copper salt is in an amount of 10 to 1,000 ppm, wherein said organic
halogen is in
an amount of 50 to 30,000 ppm, and wheren said paraffins comprise 7 or more
carbon
atoms.
The following examples illustrate the invention.
CA 02347260 2002-04-05
13
The samples tested in the following examples have been prepared and tested as
follows.
Preparation of samples
Stabilizer mixtures and Ca-stearate as lubricant are mixed with polyamide
granules and
melted in an extruder. The mixture is homogenized in the extruder and extruded
continiousfy Subsequently granules are formed. Cu concentration was always 100
ppm,
halogen concentration 1000 ppm (0.1~) and Ca-stearate concentration 0.3%.
After
drying the granules were formed into test: samples using an Infection molding
apparatus
for measuring impact strength (DIN 53453) and bending strength (DIN 53452).
Heat agoing DIN 53497 and DIN 53446
The previously prepared test samples were put in an heat oven at 130, 150 and
185°C
and were stored at these temperatures until measurements have fallen under 50%
of the
initial values. The period until this value was taken as hatftime and is the
value for the
heat ageing stability of the polyamide. This value demonstrates the effect of
the
employed stabilizers. Since many polyartiides age very rapidly without
stabilization (24h
at ~ 50°C) a use of these materials without stabilization is often not
possible.
Tracking resistance (CTI-values)
Test samples werde produced of a size of 3x5 cm (3mm thickness; infection
molding)
and tested in accordance with DIN-IEC 112.
Color determination
Discoloration of test samples was evaluated optically. In addition the color
intensity was
evaluated with the determination of the brightness (DIN 6174; DIN 5033, Part 1-
7).
Example 1
Stabilization of PA 6 , heat ageing at 150°C. Compatision with other
copper stabilizers,
addition amount 100 ppm copper. 1000 ppm halogen. Measurement of Impact
strength
until value decreases to 50% of Initial value (half value measurement);
measurement of
tracking resintance (CTl-value); color after molding and after conditioning,
color
determination (CIE Lab values; DIN 8174}.
CA 02347260 2006-09-25
14
Table 2
Type CompositionHalftime CTI-value DiscolorationDiscoloration
(h)
after after
formation conditioning
1 ComparisonPA 6 24 600 colorless Colorless
(natur)
2 ComparisonCuJ/KJ 1100 450 colorless Light green
3 ComparisonCu- 750 400 colorless Light blue
acetate/KBr
4 ComparisonCu- 800 450 Yellow-ishBlue green
stearate/KJ
Invention CuJ/PDBS 850 525 yellowish yellowish
6 Invention CuJ/DBDP 850 550 Yellowish Blue green
E
7 Invention CuJ/ 1200 550 colorless Blue green
Phosphat
1
8 Invention CuJI 900 550 yellowish Blue green
Phosphate
2
9 I InventionCuJ/TBBA 900 550 colorless Blue green
EP
oligomer
1
Invention I Cu-acetate/800 525 colorless Light blue
TBBA EP
oligomer
2
11 Invention Cu(II) 1100 500 beige ochre
acetate!
phosphate
1
CA 02347260 2006-09-25
12 Invention CuClz/ 1000 550 beige ochre
phosphate
1
13 Invention CuCI/ 900 550 beige Light blue
phosphate
1
14 Invention CuBr / 900 600 colorless Light blue
phosphate
1
15 Invention CuC03 800 600 colorless Light blue
phosphate
1
16 Invention CuJ/ 950 550 brown Brown
chloroparaffin
17 Invention CuBr/ I 900 600 beige Light brown
dechlorane
plus
18 Invention Cu- 850 600 beige Light brown
stearate/
dechlorane
plus
Table 2 (coot.)
after molding after conditioning
Type DiscolorationBrightnesDiscolorationBrightnesGreen-red Blue-yellow
L-value L-value a-value b-value
1 Colorless 68.2 Colorless 69.3 -3.2 -1.8
2 ~ Colorless 68.3 Light green66.2 -11.7 4.2
3 Colorless 69.1 Light blue 68.2 -7.8 -1.5
4 I Yellow-ish 67.5 Blue green 65.0 -7.7 2.9
5 Yellow-ish 68.8 Blue green 66.7 -9.6 -2.4
6 Yellow-ish 69.2 Blue green 68.7 -5.9 -3.2
7 Colorless 69.8 Blue green 69.2 -8.9 -1.8
8 Yellow-ish 67.3 Blue green 66.7 -5.6 6.9
i
CA 02347260 2002-04-05
16
9 Colorless68.8 Blue green68.3 -8.5 0.6
~
Colorless69.2 Light ~ 68.4 -8.8 4.0
blue
11 Beige 61.78 Ocker 59.81 ~.5 4.6
12 Beige 63.47 Ocker 61.41 -4.4 2.6
~
13 Colorless69.55 Light 67.08 -7.7 -2.1
blue .
14 i ColoHess 68.47 Light 57.71 -6.9 -2.4
blue
Colorless68.09 Light 67.32 -7.2 -2.0 ,
blue
16 Brown 22.99 Brown 22.61 2.6 6.9
17 Beige 46.42 Light 43,80 0.8 4.2
brown
18 Beige 49.81 Light 47.36 -3.7 2.8
brown
.. .,~a.a. ' p4~ ~ ~°~. ~] . Q °~.~~ EP-Oligomer 1
a~ ,, °~~ ..
EP-Oligomer 2
These results show that the polyamide compositions, stabilized in accordance
with the
invention do show slgnlflcantly improved tracking resistance and at the same
time
prolonged thermal stability. Discolorations are not detrimental for a later
coloration of the
samples of the invention.
Further experiments were carried out as above using 1000 ppm phcsphite or
phosphate_
Samples and results are given in table 2a
CA 02347260 2006-09-25
17
Table 2a
Type Composition Halftimevalue DiscolorationDiscoloration
(h) after after
molding conditioning
19 InventionCuJI 1150 600 colorless Light blue
phosphate
1/
phosphits
(23)
20 Invention(CuJ/ 1100 600 Colorless Light blue
Phosphate
1 ) in
polyamide/
phosphite
(20)
21 Invention(CuJ/ 1200 600 Colorless Light blue
PDBS) in
polyamide/
phosphite
(21 )
22 InventionCuJ/ 1100 550 Colorless Light blue
PDBS) in
polyamide/
disodium
hydrogen
phosphate
23 InventionCu(II) 900 600 colorless Light blue
stearate/
phosphate
/ phosphite
(21 )
CA 02347260 2002-04-05
1B
After molding after conditioning
Type DiscoloratiBrightnessDiscoloratiBrightnessGree-redBlue-
on L-value on L-value a-value yellow
j b-
value
19 colorless70.07 Light 6B.21 -7.7 -2.B
blue
20 Colorless73.68 Light 71 _78 -3.3
blue -8.2
21 Colorless69.96 Light 67.95 -2.7
blue ! -7.4
I
22 Colorless68,89 Light 66.21 -1.0
blue '-5.9
23 ' 68.32 66.09 -1.8
colorless ~ Llght - I -6,3
blue ~
Example 2
Stabilization of PA 66 (natur), heat ageing test at 165'C, Composltlons and
measurements as In example 1 Additional experiments with 1000 ppm phosphite or
phosphonate were done also.
Table 3
Type ComposttioHatftirneCT1-valueDiscoloratioDiscoloratio
(h)
n n after n after
formationconditlonin
ComparlsioPA 66 12 600 Colorlesscolorless
n (natur)
ComparisioCuJ/KJ 140 450 ColorlessLight
~ green
n
CompansioCu- 90 400 ColorlessLight
~ acetate/KBr blue
ComparisioCu- 90 450 YellowishBlue
green
n stearate/KJ
t Invention S25 YellowishBlue
CuJ1 green
PDBS
~ 130
'
CA 02347260 2002-04-05
19
inventionGuJI 130 550 Yellowish Blue green
DBDPE
~
InventionCuJI ~ 480 550 Colorless Blue green
Phosphatl
InventionCuCI 150 475 bei a brown
~ g
z
phosphate ' (
1 I
InventionCuGl/ 190 475 Colorises Light
blue
Phosphat
1 s
InventionCu-acatatel350 ! 475 ~ beige I brown
Phosphat
1 ~
InventionCu-acetate/120 525 colorless Light
~ blue
~
l InventionCuJI 150 550 colorless Blue green
EP- l
Oiigomer
2
InventionCuJI 330 550 beige ocker
I
dechlorane l
~
plus
InventionCuJI 370 550 brown brown
chloro
paraffinI
~ ~~
InventionGuJI 450 BOO Colorless Light
blue
phosphate
l
1l ~ l
phosphite
(20)
l
Invention(CuJ/ ~ 450 600 Colorless Light
blue
I
~ ~
PDBS)
in
polyamide/
phosphate~ ;
I (20) ~ t '
Also these samples in accorbance with the present invention do show improved
tracking
resistance and thermal stability so that the application of these samples in
the electronic
area is possible-
CA 02347260 2006-09-25
Example 3
Stabilization of PA 66, reinforced with 30°!° fiberglass (GF30),
experiments as in
example 2. Halftime values relate to bending strength. Addition amount of
phosphate
or phosphate 1000ppm.
Table 4
Type CompositionHalftime CTI- DiscolorationDiscoloration
(h)
value after moldingafter
conditioning
Comp. PA 66 GF30 120 550 Colorless Colorless
Comp. CuJ/KJ 1200 450 Yellowish Blue green
Comp. Cu-acetate/900 400 brown Brown
KBr
InventionCuJ/PDBS 900 525 yellowish Yellow green
InventionCuJ/ 1800 525 Colorless Yellowish
phosphate
1
InventionCuJI EP 1300 525 Colorless Light green
oligomer
1
InventionCuJ/ 1300 550 Colorless Light green
Phosphate
1 /
phosphate
(2)
invention(CuJIPDBS) 1400 550 Colorless Light green
in polyamide/
phosphate
(21)
Samples in accordance with the invention do show, as in previous examples CTI-
values allowing the use in electric parts.
Example 4
Stabilization of PA 66 (natur) and PA 66 GF30 with copper stabilizers,
addition of 100
ppm copper, 1000 ppm halogen, 1000 ppm phosphate or phosphonate. Measurement
of initial impact strengths: Izod with PA 66 (natur) and Charpy (not notched)
with
PA 66 GF30.
CA 02347260 2006-09-25
21
Table 5
Type Composition Halftime at Impact strength
165C (h) (kJ/m2)
Comp. PA 66 GF30 120 45 (Charily)
Comp. CuJ/KJ 1200 35 (Charily)
Invention CuJ/ Phosphate 1800 41 (Charily)
1
Comp. PA 66 (natur) 12 5.5 (Izod notched)
Comp. CuJ/KJ 140 4.0 (izod notched)
Invention CuJ/ Phosphate 480 5.5 (lzod notched)
1
Invention CuJ/ Phosphate 1400 35 (Charily) j
1/ j
phosphite (20)
in PA
66 GF30
Invention (CuJ/ PDBS) in 1200 45 (Charily)
Polyamide 66/
phosphite (21
)
Example 5
Extraction stability of PA 6 and PA 66 GF30 with water and ethanol. Evaluation
in
accordance with DIN 53738. Stabilization with 100 ppm copper and 1000 ppm
halogen, 1000 ppm phosphite or phosphonate. Determination of extract
composition after 16h reflux.
CA 02347260 2006-09-25
22
Table 6
Type Composition Amount of Composition of
extract (%) extract
Invention/Vl/aterPA 66 natur CuJ/ 0.3 No copper or halogen
Phosphate 1 or P
InventionNVaterCuJ/ Phosphate 0.3 No copper or halogen
1/
phosphite (21 or P
) PA66
natur
InventionNVaterCuJ/ Phosphate 0.2 No copper or halogen
1
PA66 GF30 or P
Invention/WaterCuJ/ Phosphate 0.2 No copper or halogen
1/
Phosphite (21 or P
) PA 66
GF30
Invention/EthanolCuJ/ Phosphate I 0.6 No copper or halogen
1/
PA6 natur or P
Invention/EthanolCuJ/ Phosphate 0.6 No copper or halogen
1/
phosphite (20) or P
PA6
natur
Invention/EthanolCuJ/ PDBS /PA6 0.5 No copper or halogen
GF30 or P
Invention/EthanolCuJ/ Phosphate 0.5 No copper or halogen
1/
phosphite (20)/ or P
PA6
GF30
Example 6
Hydrolysis stability of PA 66 GF30, decrease of mechanical properties
(hardness
and bending strength) after storage In 100% glycol, 48h at 135°C. 150
ppm copper,
1500 ppm halogen, 1000 ppm phosphite or phosphonate.
CA 02347260 2006-09-25
23
Table 7
Type compositionCTI- Ball- Bending Ball- Bending
value pressurestrength pressure strength
hardness hardness (aS)
(aS)
Comp. CuJ/KJ/ 450 141 276 91 130
KBr
InventionCuJ/ ~ 525 140 280 94 134
Phosphate
1
i
Invention(CuJ/ 525 139 278 92 ~ 132
PDBS) in
polymide/
Phosphite
(21 )
InventionCuJ/ 525 140 278 95 135
Phosphate
1/
Phosphite
(20)
i
(aS): after storage, ball-pressure hardness measured in accordance with ISO
2039/1, bending strength measured in accordance with DIN 53456
Samples in accordance with the present invention and comparative examples
show,
that the polyamide compositions of the present invention show improved long
term
temperature stability and improved maximum temperature durability and improved
tracking resistance. Also the tendency towards discoloration is reduced,
compared
with conventional polyamide compositions. Initial impact strength is affected
by use
of stabilizers in form of salts (CuJ/KJ). Substitution of KJ with soluble
costabilizers
(phosphate 1 ) reduces the decrease significantly or even avoids it. This
demonstrates the superiority of the samples of the invention.
