Note: Descriptions are shown in the official language in which they were submitted.
CA 02347258 2001-04-12
Polyamide composition, stabilized with copper complexes an:d
organic halogen compounds
The present invention relates to stabilized pvlyamide 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
embrittlemer~t with
different activity. These so-called antioxidants are mostly built on the basis
of I:~henyl
_-_ 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 fc:~r
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)
or d the
electronic industry (switches, printed circuit boards).
These copper stabilizers usually consist of two components, a mixture of
copper
' compounds and specific halogen salts. The typical copper compounds are
copper (1)
halides and copper salts, such as copper acetate, copper sulfate or copper
stearal;e and
copper complexes, such as copper acetylacetonate. In order to be effecti~~~e
as
antioxidants, halogen compounds must be added in a large surplus. Used in this
rE;~sped
are in particular potassium iodide and also potassium bromide. The employed
arnc:~unt is
typically chosen so that the molar ratio of copper to halogen is 1:5-15. The
recommended amount is generally 30 to 200 ppm copper and accordingty 150 to
3,000
ppm halogen.
These copper stabilizers lead to stabilized poiyamide products which can be
subjecaed to
thermal stress from 150 to ~ 80 °C for a short period of time, without
degradatl~~n by
CA 02347258 2001-04-12
2
ambient oxygen to embrittelment. The durability at 150 °C can be from
1,000 to 2,000
hours until the mechanical properties decrease to 50% of the initial value.
However, these commonly employed copper stabilizers do show some ~~evere
drawbacks.
Polyamides take up (conditioning) approximately 3% water. If the temperature
changes
water soluble components are extracted from the polyamide to the surtace,
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. With
electric components this may lead to failure_ If contact with metals is given
the contact
-- places will endure increased corrosion. Requirements of the electronic
industry 2nd the
automobile industry regarding the question of tracking resistance are
therefore difficult to
fulfil.
When preparing stabilized polyamides it is important to make sure that the em
Toyed
stabilizers are finely powdered and can be admixed w~tr, tr,o ~.,~"~.~,;,~~,
"~.,.
homogeneously. On problem associated therewith is usually the tendency of the
i.isually
employed components to agglomerate. The raw materials must therefore be
l;lround
very finely and must be protected against reagglomeration. The addition itself
is, due to
the minute amounts employed usually very difficult to control, therefore
usually a master
batch will be produced which will be added. Even then such a heterogeneous mix
ture of
'r solid particles in a melt is never optimal, cornpared with the hypothetical
case that the
stabilizer itself would be meltable and could be dispersed homogeneously under
working
conditions. The crystalline particles of the stabilizer salts effect the
physical properties of
the polyamides negative, even if they are finely dispersed. This does not only
res~ilt from
possible inhomogeneity but also from the fact that fine particles act as
crystals sation
nuclei which result in a higher crystallinity in polymers. This leads to
negative side
effects. The impact strength can for example decrease by 20 to 30%, compared
H~ith the
initial value of the non-stabilized polyamide.
Copper compounds furthermore lead in polyamides after conditioning often to a
bli.~ish or
greenish discoloration. Polyamides reinforced with fiber glass may furthermore
:.how 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
CA 02347258 2001-04-12
3
the production cycles, which will make the use of the produced materials for
non-colored
or colored products difficult. Therefore such polyamides are usually emplvyeni
after
black cvloration_
Copper saltlhalogen salt-Stabilizers are often added during the polymerizati
on as
aqueous solution in order to optimise the dispersion. One drawback is however
that this
addition may lead to formation of scale of metallic copper or of copper oxide
on the: metal
surface of the employed vessels and melt extruders. This may lead to vario~6on
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.
- Furthermore the durability of polyamides stabilized with conventional
stabili~,ers at
temperatures above 150 °C is not sufficient.
In view of these drawbacks several improvements were proposed.
DE-A-1237309, DE-A-1245591, DE-A-1259094 and NL-A-6501290 disclose the use of
copper phosphine complexes for the stabilization of polyamides. These
stabilize?rs are
employed in view of the improved thermal stabilization. DE-A-1245591 and DE-A-
1259094 disclose furthermore that the stabilizing activity of the copper
phosphine
complexes can be improved by addition of iodid salt.
These stabilizers are however still disadvantageous concerning tracking
resi;i,tance,
thermal stability at temperatures above 150 °C and stability against
extraction_
It is therefore the object of the present invention to provide a stabilized
polv;~amide
composition which does not show the above named drawbacks.
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 G:~mplex
of copper and at least one organic halogen compound is contained_
Furthermore the present invention provides a process for the preparation of a
stabilized
polyamide composition, comprising the mixing of at least one copper complex
and at
least one organic halogen compound with at least one poylamide.
CA 02347258 2001-04-12
4
Furthermore the present invention provides a stabilized polyamide
cornp~~sition,
characterized in that as stabilizer at least one copper complex with a
phc,sphine
compound and/or mercaptobenzimidazole compound is contained, which complex
shows
halogen-carbon-bonds.
It was found surprisingly that the stabilized polyamide composition in
accordan~:e with
the present invention is able to avoid the drawbacks of the prior art. The
drawb,~~cks of
the prior art, namely unsufficient tracking resistance, unsufficient stability
at tempe matures
above 150 °C and undesired discoloration of stabilized products, do not
occur v~~ith the
stabilized polyamide compositions in accordance with the present invention or
only to a
neglectable extent
In accordance with the present invention all typical polyarnides may be
employed.
Polyamides are polymers showing recurrent carbon amide groups -CO-NH- in the
polymer backbone. Polyamides are made from
(a) amino carboxylic acids and their functional derivatives, fvr example
lactaries; or
from
(b) diamines and dicarboxylic acids or their functional derivatives.
By varying the monomer units polyamides are obtainable in a broad variety. Th
s most
common types are polyamide 6 from e-caprolactam, polyamide 66 from
hexame~t,hylene
diamine and adipidic acid, polyamide 610 and 612, pvlyamide 11, polyamide 12,
I'ACM-
12 and polyamide 6-2-T and the aramides_
In accordance with the present invention however all further polyamides rr~~ay
be
stabilized, far example capolyamides or block copolymers of polyamides and
polyesters.
It is furthermore possible to use blends of polyamides with other polymers.
In particular preferred are polyamide 6 and polyamide 66.
In accordance with the present invention all copper complexes may by used.
'typical
examples of complex ligands are triphenyl phosphines, mercaptobenzimidazole,
EDTA,
acetylacetonate, giycin, ethylenediamine, oxalate, diethyienetriamine,
triei;hylene
tetraamine, py~dine, diphosphone arid dipyridyl.
CA 02347258 2001-04-12
These ligands may be employed singly or in combination for complex formatio i.
The
necessary snythesis are known to the skilled person or described in the
iiterat~,ire. As
usual these complexes may contain, in addition to the above-named ligands,
furtf~ ermore
typical inorganic ligands such as water, chloride, cyano etc.
Preferred are copper complexes with the ligands tripehenylphosphine,
mercaptobenzenimidazole, acetylacetanate and glycin. In particular prefewed
are
triphenyiphosphine and mercaptobenzimidazole.
Preferred copper complexes used in accordance with the present invention are
typically
prepared by the reaction of copper (I) ions with phosphine or
mercaptobenzimidazole
compounds. For example these complexes can be obtained by reacting triphenyl
_- phosphine with copper (I) halide suspended in chloroform (G.Kosta, E.
Resienhe~fer and
L.Stafani, ,!. Inorg. Nukl. chem 27 (19565) 2581), It is however possible to
react copper
(1l) compounds with triphenyl phosphine under reductive conditions, in order
to ob~l;ain the
copper (I) addition compounds (FU Jardine. !_. Rule, A.G. Vorhei, J. Chem.
Soc. (~;~) 238-
241 (1970).
The complexes employed in accordance with the present invention may however be
furthermore prepared by any suitable process. Useable copper compounds For the
preparation of these complexes are copper (I) or (1l) salts of halogen acids
or cya~t acids
or copper salts of the aliphatic carboxylic acids. Examples for suitable
copper sa:pts are
copper (I) chloride, copper (I) bromide, copper (I) iodide, copper (I)
cyanide, copper (II)
chloride, copper (II) acetate or copper (II) stearate.
In particular preferred are copper (I) iodide and copper (I) cyaniade.
Generally all alkyl or aryl phosphines are suitable. Example of phosphines
employ stile in
accordance with the present invention are triphenylphosphine and the
sub;:,tituted
triphenylphosphines, trialkylphosphines but also diarylphosphines. One exampl
a of a
suitable trialkylphosphine is tris-n-butyl phosphine. Triphenylphosphine is in
view of the
commercial availability preferred, in particular regarding economic issues.
Gener~illy the
triphenylphosphine complexes are mare stable than the trialkylphosphine
complex~:~s.
CA 02347258 2001-04-12
6
Examples of suitable complexes can be represented by the following formulae.
(Cu(PPh3)3X], (Cu2Xz(PPh~)~], (Cu(PPh3)]4, [Cu(PPH3)zX], X selected among CI,
far, CN,
SCN or 2-MBI.
Complexes which may be used in accordance with the present invention may
however
contain further complex ligands. Examples in this respect are Bipyridyl (for
eacample
CuX(PPhs)(bipy), X is CI, Br or I), Biquinoline (for example CuX
(PPh3)(biquin), ;.C is CI,
Br or I), and 1,10-Phenanthrolin, o-Phenylenebis(dimethylarsin), 1,,2_
bis(diphenylphosphino)ethan and terpyridyl.
These complexes are generally diamagnetic and electrically non-corsducting.
Tt~ey are
typically colorless and are obtained as water unsoluble crystals, which do
melt ~~Nithout
decomposition. In polar organic solvents, such as DMF, chloroform and hot
~:ahanol
these complexes are easily soluble. The melting points of these complexes are
in the
region of from 150 to 170 °C. The tetrameric copper complexes have
higher rnelting
paints of from 210 to 270 °C. Preferred are copper complexes with a
lower nunober of
phosphine ligands, from the economic point of view. Preferred are therefore in
pa-ticular
the tetrameric complexes.
The organic halogen compound may be any organic halogen compound. In ~~iew of
processing stability and for the inhibition of embrittlement due to flow out
of the rrganic
halogen compound from the stabilized polyamide composition the molecular we
ght of
the organic composition should be selected in order to secure that the
compouncl is not
easily volatile. This selection is also preferred in view of workplace
security and i i view
of the toxicolog(ca( classification of the stabilized polyamide composition.
Easily ~,~olatile
organic halogen compounds furthermore do have a strong tendency to
discoh;~ration
even though they satisfy the other requirements for the stabilizer.
Preferred as organic halogen compounds are in particular bromine con~laini~g
compounds and/or aromatic compounds.
Generally all organic halogen compounds may be employed. Examples of
si.aitable
organic halogen compounds are aromatic compounds, such as dekabromediF~henyl,
dekabromdiphenol ether, chlorinated or brominated styrene oligc:~mers,
polydibromestyrene, tetrabromebisphenyl-A, tetrabisphenyl-A derivatives, such
as epoxy
CA 02347258 2001-04-12
7
derivatives, such as BEB fi000 and BEG 500C, which formulas are given belo~N,
and
chlorinated dimethanedibenzo(a,e)cycloocten derivatives. Examples of suitable
a iphatic
compounds are chloroparafin, polyvinyl chloride, polyvinylidene clllorTde,
polytetrafiluoroethylene or fluoro rubber.
Suitable are furthermore organic compounds which contain further hetero atoms.
Examples of such compounds are halogenated aliphatic phosphates, haloganated
aromatic phosphates and halogen containing organic compounds which contain
s~llfur or
nitrogen atoms. Examples of suitable phosphates are
tris(tribromoneopentyl)phc~sphate
(phosphate 1 ) and dibromodioxaphosphorineanderivatives and chlorine
containing
polyphosphonates.
_ These compounds can be used singly or in combination.
If carbon-halogen-bonds are present in the complex of copper these born,is are
preferably carbon-bromine bands. In particular preferred are compounds
containing
TPP-Brs or 2-Mt31-Brz, in particular TPP-Br~/CuJ.
Generally all phosphines and complex ligands described before are employable;:
here,
with the proviso, that the phosphines are halogenated.
The polyamide compositions in accordance with the present invention do possess
significant advantages, compared with known stabilized polyamides_
The amount of copper complex, used in the stabilized polyamide compositions is
not
limited, as tong as the mechanical properties of the polyamide are not
affected
detrimental. Usually the amount is bet<nreen 10 and 1000 ppm copper, based on
tr~ a total
composition. Preferably 20 to 700, in particular 50 to 150 ppm copper are
employed.
The addition amount for the halogen-containing organic compound is not parti
cularly
limited. Usually amounts are added resulting in 50 to 30,000 ppm halogen,
based on the
total composition_ Preferred are 100 to 10,000, in particular 500 to 1 SOO ppm
halo~;ren.
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).
CA 02347258 2001-04-12
Higher addition amounts usually do not lead to an increase of the
stabilization effect,
polyamides containing more than 5% organic halogen containing compounds do
have a
significant lower stability. They show increased cleavage of polymer chains,
whicl~~ 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 particul
ar less
than 1 wt%.
First the thermal stability at temperatures above 150 °C is strongly
increased_
Furthermore, the stabilizing components are not water soluble, accordingly
also not
extractable with water. Therefore, the polyamide compositions in accordance
H~~ith the
present invention show the advantage vls-a-vis salt containing stabilizers
that they can
-. be employed for polyamides for electric components. Since no salts, which
would
increase the conductivity, are present or can be brought up to the surface of
the products
the requirements of a high tracking resistance (CTI-value) and a high electric
sty°ength,
which are satisfied by pure polyamides, also arE satisfied with the
pol~;iamide
compositions in accordance with the present invention.
The tracking resistance, which is determined as CTI-value is improved greatly
H~~ith the
compositions in accordance with the present invention. Accordingly the area of
practice
for the polyamide compositions in accordance with the invention is broadened
to
products which are used in the electro or electronic industry.
Polyamides for electrical products should possess CTI-values of 600, at feast
how~wer of
550. This value is reached with pure polyamide. The CTI-value is determi red
in
accordance with D1N-fEC 112_
When using conventional coppeNhalogen salt stabilizing systems failure is
often
accounted due to short cuts, in particular in view of the miniaturisation.
Simultane~:7usly a
high embrittlernent stability under prolonged thermal stress is required,
requirE:~ments
which could not yet be fulfilled simultaneously with a high tracking
resistance in
polyamides. Stabilizers on the basis of sterically hindered phenols,
phosphites or
amines, which do satisfy the electric requirements do not give the required
lorna term
durability. The long term durability could only be achieved with stabilizers
containing KJ
or KBr. Therefore, in order to achieve the desired long term thermal stability
it Haas not
possible to substitute the usual copper stabilizers, even though the
requirE:~ments
CA 02347258 2001-04-12
9
regarcJing electrical properties could not be satisfied. The polyamide
composit ors in
accordance with the present invention do satisfy both requirements. The
el~actrical
properties of the polyamines are not altered by the addition of the
stabilizing comF~onents
while simultaneously the required long term thermal stability is achieved.
The stabilizing components dissolve very good during processing in the
polyamide melt,
therefore a good dispersion and homogeneous distribution is achieved. This
simplifies
the production of these polyamide compositions. At the same time the
stabilizing
components are compatible with all sorts of polyamines. Therefore blooming at
the
processing apparatuses (nozzles, extruders, molds) and the produced pari;s and
filaments does not occur. Furthermore very good dispersion leads to im proved
mechanical properties, such as impact strength, compared with conventional
salt
-- stabilizers, far example CuJ, KJ, KBr.
Furthermore the polyamide compositions in accordance with the present
invenl:ion do
practically show no discoloration due to the stabilizing components. Therefor,
it is
possible to obtain polyamides colored with pigments, without color deviation.
Eve ~ parts
colored with TiOZ pigments do maintain their clear white color. This opens up
a further
field for colored polyamides, where a higher long term thermal stability is
required which
could however so long only be obtained with usual stabilizers, wherein however
these
have the disadvantage of their discoloration effect. The polyamide composit
ors in
accordance with the present invention therefore possess the advantage that
they ;show a
higher long term thermal stability compared with other stabilized polyamide
compositions. Furthermore the compositions in accordance with the present
invrention
are only lightly discolored, if at all.
For coloration of the polyamide compositions in accordance with the present
imnention
all common pigments are suitable, such as titandioxide, 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,
berli i blue,
ultramarine, mangan violet, cadmium yellow, schweinfurt green, molybdenum
c:~range,
molybdenum red, chromium orange and chromium red, iron oxide red, chrornoxide
green, strontium yellow, chromoxide green, molybdenum blue, chalk, ocker,
~~mbra,
green soil, terra di sienna and graphite.
CA 02347258 2001-04-12
A further advantage of the polyamide compositions of the present invention is
the
improved UV stabilization of the polyamide. The use of usual UV stabilizers,
in particular
of the so-called HALS stabilizers (Hindered Aminic Light Stabilizer) leads to
an exe;ellent
long time stabilization of polyamides which are used outdoors under the
effects of
sunlight and rain, as for example, filaments for artificial lawns and door
knobs or casings
for side mirrors in automobiles, which could not yet be obtained with common
syst~~rns.
Common stabilizing systems have the drawback of the scale formation on the
surt~~ce of
polyamide parts during continuous weathering. This scale consists of water
extracl,able
components (salts). The polyamide compositions in accordance with the present
invention do not show this drawback, no scale formation occurs. Furthermore,
prol ~nged
service life until mechanical damage of the parts is obtained. Usual
stabilizer
combinations of HALS-UV-compounds with antioxidants on the basis of sterically
hindered phenols and organic phosphites, which are employed usually, only
achieve
50% of the values found in accordance with the present invention.
The polyamide compositions in accordance with the present invention are
furthermore
excellent concerning their stability regarding hydrolysis. They show improved
tong term
stability under acidic and basic conditions, vis-a-vis salt solutions, glycol
water mixl:ures
and hot fats and oils and organic solvents. Accordingly, the usually
recognised decrease
of mechanical strength (impact strength, tensile strength) and the tendency
toward
embrittlement of the polyamides is drastically reduced and the long term
durability
enhanced.
The polyamide compositions in accordance with the present invention can
furthermore
"' be combined without limitations with further additives, such as lubricants,
plasticize~rs,
crystallization accelerators and pigments without detrimentally effecting the
desirec:l
stabilization effect. In some cases even the used additives are stabilized
against tharmal
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 invention.
Polyamides containing glass bowls, fiber glass, mineral additives or other
reinforcing
agents furthermore show, compared with common stabilizers, a significantly
improv,~ed
long-term thermal ageing stability.
CA 02347258 2004-11-17
11
The polyamide compositions In accordance with the present invention show their
improved
stability, in particular when producing polyamide filaments. Due to the
complete solubility of
the stabilizing components and due to the good compatibility with the
polyamide melt, high
addition amounts of up to 1000 ppm copper and more are possible without
processing
problems. With conventional copper halogen salt stabilizers, this is not
possible without
blooming at the spinning nozzles, leading to the disrupture of the filaments
during
processing. Furthermore, scaling of copper compounds, for example brown copper
oxide,
occurs at the extruder, scales which are difficult to remove and which may
also lead to
production problems. The polyamide compositions in accordance with the present
invention
do not show these drawbacks. The spinning of the polyamide melt is not
effected in any
way. Therefore, it is possible to continue the production over many days, even
weeks,
without unwanted discontinuations. This represents a major cost factor during
production.
Spinning of polyamide flaments is usually done starting from the melt. For
this purpose,
usually first the polyamide is melted, optionally additives are added,
subsequently the melt
is extruded through spinning nozzles. Following the hardening of the filaments
occur due to
cooling.
The production of the polyamide compositions in accordance with the present
invention can
usually be done by mixing at least one polyamide with at least one copper
compound and at
least one halogen containing organic compound. It is possible to mix the
components using
common apparatuses, namely polyamide and stabilizing compounds are mixed with
one
another and are used. 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.
CA 02347258 2001-04-12
12
It is furthermore possible to add the stabilizing components during the
production c,f the
polyamides, for example by adding them to the monomer mixture. This leads to a
~~ ery
good dispersion without any further mixing step which reduces the production
cost; 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
batcl~~ 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 employed is usually the
same
polyamide which will be mixed later with the master batch. It is, however,
also pos::ible to
_ use another polyamide or another polymer.
Furthermore, the stabilized polyamide compositions in accordance with the
present.
invention were evaluated in order to determine whether any further improvement
o11 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
phosphii;es or
inorganic phosphonates or inorganic hypophosphites. These substances are known
as
color stabilizers in polyamides. It was, however, also known that these color
stabili:!:ers
could lead often to the formation of copper oxides with copper salts.
Therefore, a grey
discoloration or brown/ black discolorations occurred. Therefore, it was
surprising tl~~at
the combination in accordance with the present invention does not lead to any
discoloration and that, furthem7ore, the blue discoloration, occurring
sometimes aft~!~r
conditioning could be reduced by the addition of organic phosphates or
inorganic
phosphonates or inorganic hypophophites. The slight discoloration occurring
durinc;~ this
mixing can be cross dyed far 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 ~~re
aliphatic as well as aromatic or mixed esters. Typical examples are, for
example,
dirnethyl and diethyl phosphate, trimethyl and methyl phosphate as well as the
additivres
known in the plastic processing industry. Typical examples are Tris(2,4-di~t-
CA 02347258 2001-04-12
13
butylphenyi)phosphite (Phosphate 20), Bis(2,4-di-t-
butylphenyl)pentaerythritoldi- ph~~sphite
(Phosphate 21 ), Tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylendiphosphonite
(Phosp kite
23), Distearylpentaerythritoldiphosphite, Diisooctylphosphite,
Distearylphosphite,
Triisodecylphosphite, Triisooctylphosphite, Trilaurylphosphite,
Tristearylphosphite,
Tris(dipropylenglycol)phosphite, Diphenylphosphite, Trisnonylphenylphosphite,
Triphenylphosphite, Trfis(p-nonylphenyl)phosphite. These compounds are
available;:
under the tradenames Irgafos, Alkanox and Weston from the companies Ciba,
We~ston
and The Great Lakes. Preferred are, in paritcular, Phosphate 20, Phosphate 21,
Ph~osphite
22 and Phosphate 23.
Usable inorganic phosphonates are salts of the phosphonic acid. Employable as
s,~it
builders are alkali metals, earth alkali metals and all other usual metals.
Preferred sre, in
particular, lithium, potassium,. sodium, magnesium, calcium, strontium, barium
and
aluminum, in particular preferred are sodium, potassium, magnesium and
calcium. A
preferred phosphonate is disodium hydrogen phosphonate.
The usable inorganic hydrophosphites are salts of the hypophosphoric acid.
Conci;;rning
the salt building, it is referred to the above metals listed in connection
with the inor~aanic
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
to~lal
composition.
The organic phosphates to be used are preferably meltable, processing stable
and stable
against extraction. This ensures that no phosphoric acid will be cleaved which
ma~~ have
disadvantageous effects for the total composition. The above given organic
phospl!~ites,
in particular the Phosphates 20, 21, Z2 and 23, satisfy the requirements
excellently,
Therefore, these compounds are particularly preferred.
It has, furthermore, been recognised during the preparation of the stabilized
polyar~ide
compositions in accordance with the present invention that the addition of the
organic
phosphate, the inorganic phosphonates and the inorganic hypophosphites should
CA 02347258 2004-11-17
14
preferably occur only after the preparation of the basic composition
stabilized with the
stabilizing components.
If a stabilized polyamide composition in accordance with the present invention
is produced
first and if the organic phosphate, the inorganic phosphonate or the inorganic
hypophosphite
is added only thereafter during an additional step, no discoloration occurs.
The above
described procedure is in particular effective with inorganic phosphonates.
The organic
phosphate, the inorganic phosphonate or the inorganic hypophosphite 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.
In another aspect, the present invention provides a stabilized polyamide
composition,
characterized an that as stabilizer at least one copper complex and at least
one organic
halogen compound is contained, wherein the at least one copper complex is a
complex of a
phosphine compound and/or mercaptobenzimidazofe compound, and wherein said at
least
one organic halogen compound comprises a halogen atom covalently bound to a
carbon
atom.
In another aspect, the present invention provides use of at least one copper
complex in
combination with at least one organic halogen compound for the stabilization
of polyamides,
wherein the at least one copper complex is a complex with a phosphine compound
and/or
mercaptobenzimidazole compound, and wherein said at least one organic halogen
compound comprises a halogen atom covalently bound to a carbon atom.
In another aspect, the present invention provides a process for the
preparation of the
stabilized polyamide composition, comprising the mixing of at least one copper
complex and
at least one organic halogen compound with at least one polyamide, wherein the
at least
copper complex is a complex with a phosphine compound and/or
mercaptobenzimidazole
compound, and wherein said at least one organic halogen compound comprises a
halogen
atom covalently bound to a carbon atom.
The following examples illustrate the invention.
CA 02347258 2004-11-17
14a
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
continiously. 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 injection molding
apparatus for
measuring impact strength (DIN 53453) and bending strength (DIN 53452).
Heat ageing DIN 53497 and DIN 53446
The previously prepared test samples were put in a heat oven at 130, 150 and
165°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 halftime and is the value for
the heat ageing
stability of the polyamide. This value demonstrates the effect of the employed
stabilizers.
Since many polyamides age very rapidly without stabilization (24h at
150°C) a use of these
materials without stabilization is often not possible.
Tracking resistance (CTI-values)
Test samples were produced of a size of 3x5 cm (3mm thickness; injection
molding) and
tested in accordance with DIN-IEC 112.
CA 02347258 2001-04-12
IJ
Color determination
Discoloration of test samples was evaluated optically, In addition the color
infensity~ was
evaluated with the determination of the brightness (DIN 6174; DIN 5033, Part 1-
7),
Example 1
Stabilization of PA 6 (natur), heat ageing at 150°C. Comparision 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 (CTI-value); color after molding and after
conditioning. Samples 20 to 26 furthermore contained 1000 ppm phosphite or
phosphonate.
' Table 1
~ ype c.ompositioHalftime Discoloratio
(h) Di:~coloratio
CTI-value
n n after ~ n 2~fter
formationconditionin
9
1 Comparisio PA 6 24 600 colorlessColorless
n (natur)
2 Comparisio CuJ/KJ 1100 450 colorlessLigl~t green
n
-- 3 Comparisio Cu- 750 400 ~ colorlessLigiit blue
n acetate/KBr
I
Comparisio Cu- 800 450 Yellow-ish81
~
u
~ green
n stearatelKJ
Invention TPP-CuCN 700 600 ColorlessCol~~rless
6 Invention MBI-CuClz500 600 Yellow-ishYellow-ish
7 Invention TPP-CuJI 1400 600 I colorlessAlmost
Phosphat
1
colc:~rless
Invention TPP-CuJ/ 1200 600 colorlessAlmost
PDBS
colt: rless
Invention TPP-CuCN/1400 600 colorlessCol~:~riess
~
Phosphat I
1
CA 02347258 2001-04-12
16
Invention MBI-CuJI 950 600 Yellow-ishYellow-ish
Phosphat1
11 Invention TPP-CuJI 550 6D0 colorless Cr~lorless
teflon
wax
12 f nventionTPP-CuJ/ 1200 6017 - colorless Lirlht
- blue
TBBA-EP-
Oligomer
~
13 Invention MBI-CuJ/ 1000 600 colorless Liclht
yellow
TBBA-EP-
Oligomer
2
14 Invention TPPBr2- 1200 600 colorless Lirlht
green
CuJ
Invention TPP-CuJ/ 1100 600 Light brownDrark brown
chloro-
paraffin
-
16 Invention TPP-CuJ/ 1200 600 beige Br~~wn
Dechlvrane
plus
17 Invention Cu-glycine/950 600 beige BEiige
Phosphate
7
18 Invention Cu-acetyl900 600 White greyGreen
acatonate/ beige
_ Phosphate
1
19 Invention MBI-CuCll1050 600 colorless Lic;lht
green
Phosphate
1
Invention TPP-CuJ/ 1100 600 colorless Lic:lht
blue
Phosphate
1I
Phosphite
( 20)
CA 02347258 2001-04-12
17
21 InventionTPP-CuJ/ 1200 600 colorlessLcw
Phosphate
1I
Phosphate
(21 )
22 InventionTPP-CuJ/ 1100 fi00 colorlessLc~w
PDBS/
Phosphate
(22)
23 InventionTPP-CuJ/ 1150 600 colorlessLc~w
Phosphate
1/
- Phosphate
(23}
24 invention(TPP-CuJ/ 1100 500 colorlessLc~w
Phosphate
1 ) in
Polyamid/
Phosphate
{20)
25 Invention(TPP-CuJ/ 1200 600 colorlessLc w
PDBS) in
Polyamid/
Phosphate
__
(21 )
26 Invention(TPP-CuJ/ 1100 550 colorlessLo w
PDBS) in
Polyamid/
Disodiumhy
drogenphos
phonate(24
These experiments demonstrate the superior effect of the stabilizers employed
in
accordance with the present invention concerning tracking resistance and
thermal
stabiiity_
CA 02347258 2001-04-12
18
Table 1 (cont.)
Color determination, polyami;de test samples
(CIELab-values, DIN 6174)
after molding after conditioning
Type DiscoloratioBrightnessDiscoloratioBrightnessGreen-red BG~e-yellow
n L-value n L-value a-value b-~ialue
1 Colorless68.2 Colorless69.3 -3.2 -1.g
2 Colorless68.3 Light 66.2 -11.7 4.;;>
green
3 Colorless69.1 Light 68.2 -7_g _1.5
blue
4 Yellow-ish67.5 Blue green65.0 -7.7 2.t'1
Colorlessfi9.7 Colorless69.8 -3,3 -1,5
6 Colorless69.1 Light 69.9 -7.3 -3 ~5
blue
7 Colorless70.2 Yel low 69.8 ~ -6.3 0.>
green
8 Colorless67.3 Blue green69.3 -7.4 1..'i
Colorless69.8 ~ Almost 69.3 -3.5 O.E:.
colorless
Colorless69.2 Almost 71.9 -5.2 0..
colorless
11 Colorless69,7 Light 68.4 -8.8 4.(;~
blue
12 Colorless69.0 Almost 69.3 -7.5 -1..?
colorless
13 Colorless69.3 Yellow 69.9 -6,5 3.c,
green
14 Colorless70.2 Light 69.8 -g.7 4.;
16 Beige 53.17 green 48.54 -12.4 -8_-T
Brown
17 Beige 66.94 Beige 66.39 -~ _6 p.;
18 White 69.79 Green 68.39 -3.6 O.C. .
grey beige
19 70.63 Light 69.04 -6,7 2,~i
Colorless green
Colorless62.13 Light 59.81 -3.5 _1.~;;
blue
21 Colorless63.72 Light 59.41 -3.4 _1.;;;
blue
22 Colorless61.86 Light 58.08 -3.1 _1.;;;
blue
23 Colorless64.07 Light 60.21 -3.7 _ 1.;;
blue
24 Colorless64.68 Light 65.78 4.2 - 3.:;;
blue -
CA 02347258 2001-04-12
19
25 Colorless65.96 Light 65.95 -4.4 -2~ 7
blue ~
26 ~ ColorlessI 62.89 I Light 59_21 ..3,g _1' p
blue
Q ~~~ ~ ~~, Q ~-~ g ~ r EP-Oligomer 1
a~. ~ a., a..
EP-Oligome ~ 2
Example 2
Stabilization of PA 66 (natur), heat ageing test at 165°C,
Compositions and
measurements as in example 1
CA 02347258 2001-04-12
Table 2
Type CompositioHalftirneCTI-value DiscoloratioDiscoloratio
(h)
n n after n after
formationconditionin
9
ComparisioPA 66 12 600 Colorlesscolorless
n (natur)
ComparisioCuJ/KJ 140 450 ColorlessLight green
n
ComparisioCu- 90 400 ColorlessLight blue
n acetatelKBr
ComparisioCu- 90 450 YellowishBlue green
n stearate/KJ
ComparisioTPP-CuJ 80 500 ColorlessBluefish
n
ComparisioMBI-CuJ 60 600 ColorlessYellowish
n
Invention TPP-CuJ/ 430 600 ColorlessAlmost
Phosphat colorless
1
Envention TPP-CuJ/ 180 600 ColorlessAlmost
PDBS colorless
.-. Invention TPP-CuCN/250 600 ColorlessColorless
Phosphat
1
Invention MBI-CuJ/ 170 600 YellowishYellowish
Phosphat
1
Invention TPP-CuJ/ 110 600 colorlessC4lorless
teflon
wax
Invention TPP-CuJ/ 180 600 cotorlessBlue green
EP-
Oligomer
1
Invention MBI-CuJ/ 180 600 colorlessLight yEllow
EP-
Oligomer
2
CA 02347258 2001-04-12
21
InventionTPPBrs- 220 600 colorless Light
green
CuJ
InventionTPP-CuJ/ 110 600 Colorless colorless
Viton
InventionTPP-CuJ/ 90 600 Colorless Light
' blue
PDBS/
Phosphate
(20)
InventionTPP-CuJ/ 350 600 colorless Light
blue
Phosphate
1l
Phosphate
._ (21 )
InventionTPP-CuJ/ 350 600 colorless Light
blue
PDBS/
Phosphate
(20)
Invention(TPP-CuJI29D 60D colorless Light
blue
Phosphate
1 ) in
Palyamid!
Phosphate
(20)
-_ Invention(TPP-CuJ/170 550 colorless Light
blue
PDBS)
in
Polyamid/
Dinatriumh
ydrogenpho
s phonate(2
4 )
As shown in example 1 the samples in accordance with the present invention do
stnow
improved tracking resintance and therTnal stability
CA 02347258 2001-04-12
22
Example 3
Stabilization of PA 66, reinforced with 30% fiberglass (GF30), heat ageing
test at 165°C,
Measurements as in example 1. Ratios as in example 1. Halftime values relate
to
bending strength.
Table 3
Type CompositionHalftime CTI-value DiscolorationDiscoloration
(h)
after moldingafter
conc:litioning
Cornp. PA 66 GF30 120 550 Colorless Colc rless
Comp. CuJ/KJ 1200 450 Yellowish Blues green
Comp. Cu-acetate/900 400 brown Broom
KBr
Invention TPP-CuJ/ 1600 550 Colorless Almost
Phosphat Colc,rless
1
Invention TPP-CuJ/ 900 550 Colorless Colc:rless
teflon wax
Invention TPP-CuJ/ 1300 550 Colorless Ligh t green
phosphat
1 /
phosphate
(2D)
Invention (TPP-CuJ/ 1400 550 Colorless Ligh t green
PDBS) in
polyamide/
phosphate
(21 )
Samples in accordance with the invention do show, as in examples 1 and 2
reduc~,~d
tendency to discoloration.
Example 4
Stabilization of PA 66 (natur) and PA 66 GF30 with copper stabilizers,
addition of ° OD
ppm copper, 1000 ppm halogen, 1000 ppm phosphate or phosphonate. Measurem ant
of
initial impact strengths: Izod with PA 66 (natur) and Charily (not notched)
with PA p6
GF30
CA 02347258 2001-04-12
23
Table 4
Type Composition Halftime at 165CImpact stren~ath
(h)
. (kJ/mz)
Comp. PA 66 GF30 120 45 (Charily)
Comp. CuJIKJ 1200 35 (Charily)
Invention TPP-CuJ/ Phosphate160D 45 (Charily)
1
Comp. PA 66 (natur) 12 5.5 (Izod not~:hed)
Comp. CuJ%KJ 140 4.0 (Izod nota:hed)
Invention TPP-CuJ% Phosphate430 5.5 (Izvd not~,:hed)
1
Invention TPP-CuJ/ Phosphate1400 35 (Charily)
1/ phosphate
(20)
Invention (TPP-CuJ/ PDBS) 1200 45 (Charily) .
in
Polyamide/ phosphate
(21 )
Even mechanical properties of stabilized polyamides are improved in accordance
math
the present invention.
Example 5
Extraction stability of PA 6 and PA 66 GF30 with water and ethanol. Evacuation
in
accordance with DIN 53738. Stabilization with 100 ppm copper and 1000 pprn
halo~~en,
1000 ppm phosphate or phosphonate. Determination of extract composition after
16,~
reflux.
CA 02347258 2001-04-12
24
Table 5
Type Composition Amount of extractComposition of
(%) extract
Comp.Mlater PA 66 (natur) 0.4 Ca~prolactarr~
a an
oligomers
Comp./Water CuJ/KJ 0.5 As above arid
KJ,
CuJ
InventionM/ater TPP-CuJ/ PDBS 0.3 No copper o~~
halogen
Invention/Water MBI-CuJ/ Phosphate0.3 No copper o halogen
1
Comp_/Water PA66 GF30 0.3 AH salt, oliga~mers
Comp./Water CuJ/KJ 0.4 As above, K,J,CuJ
Invention/Vl/aterTPP-GuJ/ PDBS 0.2 No copper o r
halogen
Invention/Water MBI-CuJ/ Phosphate0.2 No copper or halogen
1
Comp./Ethanol PA 6 (natur) 0.8 Caprolactanne
an
oligomers
Comp./Ethanol CuJ/KJ 0.9 As above and KJ,
CuJ
Invention/EthanoiTPP-CuJ/ PDBS 0_fi No copper c~r
halogen
InventionlEthanolMBI-CuJ/ Phosphate0.6 No copper c~r
w halogen
Gomp./Ethanol PA 66 GF30 0.6 AH salt, oligomers
Comp./Ethanol CuJ/KJ 0.6 As above, KJ,CuJ
Inventlon/EthanolTPP-CuJ/ PDBS 0.5 No copper ar halogen
Invention/EthanolMBI-CuJ/ Phosphate0.5 No copper car
1 halogen
Invention/Water PA 66 (natur):TPP-0.3 No copper cir
CuJ/ Phosphate halogen
1/
Phosphite (20)
CA 02347258 2001-04-12
Invention/Water PA 66 GF30 : TPP-0.2
No copper cr halog
CuJ/ Phosphate
1/
Phosphite (20)
lnvention/EthanolPA 6 (natur):TPP-0.6 No copper ar halogen
CuJ/ Phosphate
1/
Phosphite (20)
Invention/EthanolPA 6 GF30 ; TPP- 0.5 No copper car
halogen
CuJ/ Phosphate
1/
Phosphite (20)
Samples in accordance with the present invention do show improved extraction
staability,
in particular no copper and/or halogen compounds are extracted. This is
advantageous
in view of applications in electronic parts and in the area of cosmetics,
pharmaceu~licals
and nutrition.
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, 15;)0
ppm halogen, 1000 ppm phvsphlte or phosphvnate.
Table 6
Type compositio CTI-value Ball- Bending Ball- Bending
- n pressure strength pressure strangth
hardness hardness (a:
(aS)
Comp. CuJ/KJ/ 450 141 276 91 130
KBr
Invention TPP-CuJ/ 550 139 277 96 13 5
Phosphate
7
Invention MBI-CuJ/ 550 138 274 g5 ~3~g
Phosphate
1
CA 02347258 2001-04-12
26
InventionTPP-CuJ/ 550 140 278 95 1 ~i5
Phosphate
1I
Phosphate
(20)
(aS): after storage, ball-pressure hardness measured in accordance with ISO
203~;~/1,
bending strength measured in accordance with DIN 53456
Samples in accordance with the present invention do show improved tracking
resi;,;tance
and better mechanical properties after storage. The tests in accordance with
the present
invention show that with the polyamide compositions in accordance with the
invention
improved tracking resistance and improved long term durability can be
obtained.
Furthermore the lower tendency towers discoloration of the polyamide
composition of the
present invention is demonstrated.
Example 7
Use for the preparation of polyamide filaments (PA 6 and PA 66)
Processing. Stabilization with 60 ppm copper, 500 ppm Br due to addition of
TTP-
CuJ/Phosphate 1 or MBI-CuJ/PDBS. Further tests with stabilization with TPP-
CuJ/Phosphate 1/Phosphite (20), 200 ppm Cu, 2000 ppm Br, 1000 ppm Phosphite~.
1. No scale formation during filament formation (PA 66), no irltem.~ption
during 1 ~I days,
color even without variation.
2. White colored PA 6.12 monophiles, no problems, even color.
With usual copper stabilizers every 1 or 2 days filment ruptures occur due to
bloort'iing of
copper compounds (plate out).
Heat aging stabilization: Stabilization as above
Evaluation: max. decrease of 5% offer 4h at 175°C (ASTM, elongation at
break}
CA 02347258 2001-04-12
2~
Always satisfied, with further addition of phosphite further improvement of
color, further
improved weatherability.
Polyamide compositions in accordance with the present invention are
particularly suited
for the preparation of tyre cord_ Usual stabilizers are prepared with the so
called ENKA
process. Aqueous solutions of stabilizers are sprayed over polyamide granulra,
the
solution penetrates and the granules are dried. One severe drawback of
m;;aterials
produced from these granules is the presence of water soluble copper
comF~ounds,
which, in tyres, my tend to migrate into the surrounding rubber. This leads to
acce erated
aging of the tyre since copper acts as rubber poison, in partucular concerning
I=PDM.
This draw back does not occur with the polyamide of the invetion_
